LIBRARY 

OF  THK 

UNIVERSITY  OF  CALIFORNIA. 

GIFT  OF 

MRS.   MARTHA   E.   HALL1DIE. 
Class 


A 

TREATISE  ON  ACOUSTICS 


IN    CONNECTION   WITH 


VENTILATION; 


Modern  and  Ancient  Methods  of  Heating  and  Ventilation, 

BY  ALEXANDER  SAELTZEB, 

ABCHTTECT. 


(  'UNIVERSITY 

„ 

NEW  YORK: 
D.    VAN    NOSTRAND,    PUBLISHER, 

23  MURRAY  STREET  AND  27  WARREN  STREET. 

1872. 


Entered  according  to  act  of  Congress,  in  the  year  1872,  by 

D.  VAN  NOSTRAND, 
in  the  Office  of  the  Librarian  of  Congress  at  Washington. 


PREFACE. 


It  appears  to  me  necessary  to  make  a  few  remarks 
in  advance,  as  I  am  anxious  the  book  which  I  herewith 
lay  before  the  public,  should  at  least  receive  a  friendly 
acknowledgment  of  the  many  days'  and  even  months' 
time  of  my  strictest  observation.  The  title  of  this  book 
embraces  much  that  is  of  great  importance,  especially 
on  the  subject  of  acoustics,  as  the  problem  introduced 
in  it  which  I  have  endeavored  to  explain  and  to  vindi- 
cate, will  prove. 

It  is  the  first  attempt,  in  its  peculiar  nature,  ever 
presented  to  the  public  ;  at  least  I  believe  that  all  the 
former  experience  upon  the  subject  of  acoustics,  refer- 
ring to  public  buildings,  may  be  placed  in  a  secondary 
light,  without  fear  of  being  considered  arrogant.  There 
must  be  a  good  cause  why  this  proposed  theory  has 
not  been  advanced  by  any  other  higher  professional 
pen  previously.  And  surely  the  cause  is  clear,  as  sci- 
ence in  this  particular  branch  is  too  youog,  and  it  is 
only  in  this  nineteenth  century  that  the  nature  of  sound 
has  been  partially  discovered.  A  large  field  is  still 

103278 


4  PKEFACE. 

open  ;  many  obstructions  will  have  to  be  cleared  away, 
and  many  individuals  will  have  to  assist,  with  manifold 
labor,  to  concentrate,  and  confine  progressively,  the 
harmonious  dictates  of  nature.  I  have  been  often 
placed  in  a  very  unpleasant  position,  in  the  construc- 
tion of  public  buildings,  where  acoustics  have  formed 
a  most  important  part,  and  in  which  the  want  of  knowl- 
edge on  sound  has  caused  a  feeling  of  actual  discour- 
agement to  proceed,  and  I  have  no  doubt  many  archi- 
tects have  found  themselves  in  the  same  predicament. 
This  new  theory  will  obviate  this  uncertainty,  as  well 
as  confine  and  regulate  sound  in  its  proper  course  and 
action,  and  in  being  found  correct  will  justify  me  for 
the  expression  of  my  inmost  conviction. 

A.  SAELTZEE, 

Architect. 

NEW  YORK, 

49  WaU  street. 


ACOUSTICS. 


ANY  practical  fact  relating  to  science  can  never  be 
traced,  except  through  the  thorough  knowledge  of 
nature,  and  our  progress  in  this  sphere  will  always  be 
either  checked  or  advanced  accordingly. 

This  new  and  important  discovery  will  undoubtedly 
prove  these  assertions,  and  will  produce  a  plain  and 
striking  example,  which,  I  hope,  will  assist  all  future 
arrangements  and  do  away  with  all  the  existing  evils 
in  public  halls  or  buildings,  at  least  as  much  so  as 
possible,  and  the  changes  will  be  precisely  in  propor- 
tion to  the  application  of  the  new  remedy  to  the  exist- 
ing mismanagement  of  form,  proportion,  and  construc- 
tion heterogene  to  nature. 

Sound  receives  its  vitality  or  its  life  through  the  air, 
and,  without  air  sound  loses  it  and  becomes  extinct. 

Before  I  proceed  to  explain  the  new  discovery,  I  will 
first  introduce  a  number  of  facts  showing  the  relative 
attributes  of  sound  in  connection  with  air,  from  the 
best  authorities,  not  alone  as  being  interesting,  but  as 
a  necessity,  for  the  remedy  which  I  propose  for  build- 
ings of  all  classes  where  sound  has  proved  a  failure. 

"  The  intensity  of  sound  depends  on  the  density  of 
"  the  air  in  which  sound  is  generated,  and  not  on  that 
"  of  the  air  in  which  it  is  heard.  A  feeble  sound 


6  ACOUSTICS. 

"  becomes  instantly  louder  as  soon  as  the  air  becomes 
"  more  dense.  So  you  will  always  find  on  great  eleva- 
"  tions  in  the  atmosphere  the  sound  sensibly  diminished 
"  in  loudness.  If  two  cannon  are  equally  charged  and 
"  one  fired  at  the  top  of  a  high  mountain  and  the  other 
"  in  a  valley,  the  one  fired  below  in  the  heavy  air  may 
"  be  heard  above,  while  the  one  fired  in  the  higher  air 
"  will  not  be  heard  below ;  owing  to  its  origin,  the 
"  sound  generated  in  the  denser  air  is  louder  than  that 
"  generated  in  the  rarer.  Peals  of  thunder  are  unable 
"  to  penetrate  the  air  to  a  distance  commensurate  with 
"  their  intensity,  on  account  of  the  non-homogeneous 
"  character  of  the  atmosphere  which  accompanies 
"  them ;  from  the  same  cause  battles  have  raged  and 
"  have  been  lost  within  a  short  distance  of  the  reserves 
"  of  the  defeated  army  while  they  were  waiting  for  the 
"  sound  of  artillery  to  call  them  to  the  scene  of  action." 
Science  teaches  us,  that  whenever  a  shock  or  pres- 
sure of  any  sort  is  suddenly  applied  to  any  material  of 
any  nature,  whether  metal,  wood,  gas,  water,  air,  etc., 
it  is  immediately  affected  in  all  its  parts,  from  the  point 
of  contact  to  the  whole  extent  of  the  material,  in  dis- 
placing and  replacing  the  particles  of  a  determinate 
volume ;  and  the  velocity  of  the  movement  of  the  par- 
ticles of  the  mass  created  by  the  concussion  of  shocks 
or  pressure  depends  solely  upon  the  nature  of  any 
material,  upon  its  elasticity  and  density ;  sound  likewisa 
causes  motions  with  every  particle  of  the  air,  and  as 
far  as  the  motion  reaches,  so  that  each  particle  with 
regard  to  that  which  lies  immediately  beyond  it,  is  in 


ACOUSTICS.  7 

a  progress  of  rarification  during  return.  "All  parts 
which  go  forward  do  in  their  progressive  motion  strike 
each  obstacle  they  meet  in  their  way ;  they  are  for  that 
reason  called  pulses,  and  the  sensations  which  are  ex- 
cited in  the  mind  by  the  strokes  of  these  pulses  on  the 
drum  of  the  ear  are  called  sounds,  considered  in  their 
physical  causes  are  nothing  else  than  the  pulses  of  the 
air."  "In  order  therefore  to  explain  the  nature  of 
sound  I  will  add  the  chief  properties  of  these  pulses. 
The  first  is,  that  they  are  propagated  from  the  trem- 
bling body  all  around  in  a  spherical  manner.  For  the 
pulses  go  and  return  according  to  certain  directions 
from  the  parts  of  the  body  by  whose  vibrations  they 
are  generated ;  yet  for  as  much  as  every  impression 
which  is  made  on  a  fluid  is  propagated  every  way 
throughout  the  fluid,  whatever  be  the  direction  wherein 
it  is  made  in  like  manner  the  pulses  must  spread  and 
dilate  so  as  to  form  themselves  into  concentric  spheri- 
cal surfaces,  or  rather  shells,  whose  common  centre  is 
the  place  of  the  sounding  body.  And  hence  appears 
the  reason  why  one  and  the  same  sound  may  be  heard 
by  several  persons,  though  differently  situated  with 
respect  to  the  sounding  body." 

"A  second  property  of  the  pulses  is  that  they  grow 
less  and  less  dense  as  they  recede  from  the  sounding 
body,  and  in  the  same  proportion  with  the  squares  of 
their  distances  from  the  body.  For  whatever  be  the 
force  wherewith  the  sounding  body  acts  on  the  first 
spherical  shell  of  air,  with  the  very  same  force  does 
that  shell  act  upon  the  second,  and  that  again  upon 


8  ACOUSTICS. 

the  third,  and  so  on  continually,  so  that  the  force  which 
condenses  the  air  in  the  several  shells  is  given ;  conse- 
quently the  condensation  which  it  produces  in  those 
shells  must  be  inversely  as  the  resistance  it  meets  with 
but  the  resistances  are  at  each  shell,  and,  therefore, 
since  they  increase  continually  in  the  same  proportion 
with  the  squares  of  their  distance  from  the  centre,  their 
density  must  increase  in  the  same  manner.  By  reason 
of  their  diminution  in  the  densities  of  the  pulse's,  those 
which  are  further  removed  from  the  sounding  body 
make  lighter  impressions  on  the  drum  of  the  ear  than 
those  which  are  less  distant,  and  hence  it  is  that 
sounds  grow  less  and  less  audible,  the  further  they  go 
from  the  sounding  body,  and  at  certain  distances  be- 
come so  weak  as  not  to  be  heard  at  all." 

"  A  third  property  of  the  pulses  is,  that  all  of  them, 
whether  denser  or  rarer,  move  equally  swiftly,  so  as  to 
be  carried  through  equal  spaces  in  equal  time.  From 
this  property  it  follows  that  all  sounds,  whether  they 
be  loud  or  low,  grave  or  acute,  move  equally  swiftly ; 
the  softest  whisper  making  equal  speed  with  the  noise 
of  a  cannon,  or  the  loudest  thunder  clap ;  and  it  has 
been  found  by  experiment  that  sounds  move  at  the  rate 
of  1,142  feet  in  a  second  of  time,  or  thereabouts,  for 
the  velocity  is  not  precisely  the  same  in  all  seasons  of 
the  year,  but  is  somewhat  greater  in  summer  than  in 
winter,  on  account  of  the  heat,  which  renders  the  air 
more  elastic  in  proportion  to  its  density  than  it  is  in 
the  cold  winter  season." 

Any  room,  hall,  church,  etc.,  or  any  space  enclosed 


ACOUSTICS.  9 

by  walls,  ceiling  and  floor,  compresses  the  air  in  a  state 
of  greater  density  compared  with  the  atmospheric  air, 
and  consequently  the  sound  in  such  places  should 
always  be  more  distinct  than  the  sound  in  the  open 
air  in  proportion  to  a  determinate  volume,  a  fact  which, 
is  of  importance  and  which  has  been  demonstrated 
sufficiently.  Now,  if  we  take  even  a  one-sided  view  of 
the  case,  which  represents  itself  conclusively,  this  ad- 
vantage of  great  density  alone  would  be  sufficient  to 
assist  sound  for  any  practical  purpose,  but  this  is  not 
the  case,  and  why  ?  The  density  of  the  air  in  those 
rooms  is  generally  in  an  unhealthy  state,  heterogeneous 
to  the  nature  of  sotyid,  and  even  to  health  itself,  from 
various  causes  which  I  will  explain  more  in  detail. 

It  has  been  mentioned  before  that  the  air  is  strongly 
affected  by  cold,  heat,  dampness,  gases,  etc.,  and  in 
proportion  as  the  air  varies  from  the  pure  state  to  too 
much  dampness,  too  much  cold,  etc.,  the  vitality  of  tho 
sound  is  more  or  less  affected.  Next  follows  the  mix- 
ture of  different  strata  of  air,  which  will  each  affect  the 
sound  more  or  less  in  its  propelling  power,  the  densi- 
ties of  the  strata  of  air  differing  ;  this  difference  in  the 
state  of  air  is  found  also  in  empty  rooms. 

In  halls,  churches,  theatres,  etc.,  crowded  with 
people,  the  density  of  the  air  increases  by  the  bodies 
still  more ;  but  this  increase  of  density  is  balanced 
somewhat  by  the  loss  of  reflection. 

We  often  find  theatres  or  churches  filled  with  gloomy 
air  before  they  are  occupied  ;  and  if  the  air  exhaled  by 
thousands  of  psople  assembled  be  added,  it  causes  a 


10  ACOUSTICS. 

perfect  revolution  of  different  strata  of  air,  even  more 
adverse  to  the  development  of  intelligible  sound.  The 
bad  air  which  is  created  by  exhalation  is  heavier 
than  all  the  rest,  except  atmospheric  air,  and  natu- 
rally sinks  to  the  lower  portion  of  the  hall  and  dif- 
fuses itself,  the  more  so  where  there  are  galleries ;  and 
precisely  in  proportion  as  this  bad  air  increases  in 
volume  the  sound  becomes  less  and  less,  in  a  theatre  it 
being  noticeable  first  in  the  pit,  then  in  the  first  gallery, 
and  so  on  upwards  ;  and  hence  you  will  often  notice 
that  in  the  upper  galleries,  or  upper  parts  of  the  house 
the  hearing  is  more  distinct.  Bad  air,  it  is  true,  be- 
comes much  more  dense,  but  the.  substances  of  this 
air  are  poison  to  the  vitality  of  the  sound,  as  well  as 
to  health,  mind,  lungs,  and  voice,  and  this  proves  that 
sound  can  only  carry  out  its  function  when  well  sup- 
plied with  healthy  and  congenial  air.  If  you  notice 
the  changes  of  sound  in  crowded  houses,  and  follow  its 
diminishing  state  of  existence,  you  will  first  find  its 
nature  often  in  tolerably  good  humor,  then  it  becomes 
delirious,  and  is  placed  in  a  most  uncomfortable  posi- 
tion, not  knowing  whicli  way  to  turn ;  poison  on  all 
sides,  ever  anxious  to  do  its  duty,  full  of  its  natural 
vitality,  it  becomes  disheartened,  leaves  first  its  battle 
field,  the  pit,  next  the  first  gallery,  then  the  second, 
third,  etc.,  and  at  last,  exhausted,  looks  up  as  high  as 
possible  to  gain  rest  in  the  strata  of  warmer  and  more 
flexible  air,  air  more  congenial  to  its  nature,  which  is 
always  found  at  the  highest  point. 

This  is  a  true  picture  of  the  condition  of  sound  in 


ACOUSTICS.  11 

theatres,  etc.,  where  there  is  not  a  proper  ventilation  ; 
and  why  has  ventilation  not  been  applied  for  this  pur- 
pose of  propagating  sound?  Because  ventilation  is 
comparatively  new,  and  is  hardly,  or  very  little  under- 
stood in  its  proper  light ;  in  its  effect  upon  sound  in 
buildings  no  such  idea  has  as  yet  become  known,  and 
it  is  strange,  but  nevertheless  true,  that  there  cannot 
be  found  a  book  on  acoustics,  that  I  am  aware  of,  in 
which  ventilation  is  mentioned  in  connection  with  it. 
Ventilation  here  forms  the  most  important  part  in  the 
consistency  of  nature,  and  if  only  properly  and  scien- 
tifically executed,  the  greatest  point  is  gained  ;  form, 
however,  and  construction,  proportion,  and  size,  ma- 
terials, and  even  art  has  to  be  introduced  to  form  a 
combination  or  amalgamation  to  gain  success,  and  to 
be  truthful  to  the  dictates  of  nature,  which  never 
deceives. 

Architects  hitherto  have  considered  form  and  ma- 
terial and  size  the  only  prominent  features  to  assist 
sound,  and  hence  the  uncertainty  of  the  results.  The 
prevailing  opinion  is  also  established,  that  vaulted  an.l 
curved^  roofs  and  ceilings  act  as  mirrors  upon  sound. 
In  one  of  the  cathedrals  in  Sicily  the  Confessional  was 
so  placed  that  the  whispers  of  the  penitents  were  re- 
flected by  the  curved  roof,  and  brought  to  a  focus  at  a 
distant  part  of  the  edifice.  There  is  also  a  whisper- 
ing gallery  in  St.  Paul's  Cathedral  in  London,  a  moot 
astounding  phenomenon,  a  mere  accident  not  calcu- 
lated upon  originally.  Now,  if  we  rest  upon  the  as- 
sumption that  a  pure  air,  genial  to  sound,  guides  tlie 


12  ACOUSTICS; 

path  of  sound,  this  mystery  is  solved  at  once.  I  will 
here  explain  how  such  a  singular  case  may  be  effected. 
The  St.  Paul's  Cathedral,  in  London,  and  the  Cathe- 
dral in  Sicily  are  large  edifices,  with  exterior  as  well  as 
interior  walls  of  solid  masonry ;  they  are  only  used  on 
particular  occasions,  and  ventilation  is  entirely  foreign 
to  them,  and  the  consequence  is  that  the  air  in  them  is 
almost  like  cellar  air,  damp  and  heavy,  inclined  to  stop 
the  pulses  created  by  sound,  in  consequence  of  which 
the  lower  strata  of  air  are  repulsive  to  sound.  All  the 
Warmer  and  more  elastic  air  at  the  highest  point  in 
such  buildings  is  always  created  by  a  draft  of  air  from 
doors  and  windows,  and  somewhat  vitalized  by  the 
sun  reflecting  its  warmth  through  the  windows,  no 
matter  what  the  colors  of  the  glass  may  be  ;  although 
some  colors  have  the  tendency  to  draw  heat  more  than 
others.  The  air  introduced  into  these  buildings  by 
draft  from  the  outer  atmosphere  is  often  lighter  and  of 
better  quality  than  the  inner  air,  and  rises  according 
to  its  flexibility  to  the  higher  places  under  the  ceiling, 
and  a  somewhat  continued  draft  will  certainly  have  the 
tendency  to  clarify  the  interior  air  of  a  dome,  for  in- 
stance, like  that  of  St.  Paul's  Cathedral,  and  it  will 
always  be  a  focus  of  attraction,  especially  where  there 
is  much  light  introduced,  even  without  escape  of  air. 
Now  let  us  trace  our  steps  to  the  Confessional,  and  fol- 
low the  voice  from  the  pastor's  lips,  and  his  position. 

The  pastor  is  situated  in  the  Confessional,  a  box  or 
tube  in  form.  In  this  tub 3  the  air  is  more  dense  than 
the  surrounding  air,  and  it  gains  more  vigor,  the 


ACOUSTICS.  13 

pastor's  head  being  about  5  feet  or  sometimes  more 
above  the  level  of  the  church  floor,  his  voice  strikes 
above  the  lower  strata  of  damp  air,  which  are  the 
heaviest ;  and,  as  the  strata  become  lighter  and  more 
elastic  according  to  their  elevation,  it  is  natural  that 
the  sound  rises  immediately  to  the  higher  strata  and 
continues  under  the  ceiling  to  a  certain  distance,  till  it 
strikes  a  volume  of  air  which  has  been  revolutionized 
by  draft  from  the  outside  or  to  a  locality  where  those 
influences  are  mostly  concentrated,  and  hence  the 
downward  movement  of  the  sound  to  the  lower  part  of 
the  building  and  to  a  distinct  place  ;  in  fact  the  sound 
marches  swiftly  beyond  the  heavy  volumes  of  air  con- 
tained in  the  body  of  the  church,  and  seeks  a  path 
downwards  as  soon  as  nature  assists.  Now,  some 
might  take  it  for  granted  that  this  same  effect  might 
be  gained  by  placing  the  Confessional  in  another  situa- 
tion, and  it  would  likely  prove  a  failure  ;  but  this  "would 
be  no  criterion,  no  proof  whatever,  against  the  theory 
advanced,  because  light  may  be  more  effective  on  one 
side  than  on  the  other,  the  draft  of  air  also  may  be 
more  on  one  side  than  on  the  other ;  much  also  will 
depend  on  the  situation  of  the  building  itself. 

The  theory  advanced  will  also  abolish  sound-boards 
over  pulpits ;  how  is  it  possible  that  a  sound-board, 
even  8  or  10  feet  square  or  circular,  should  cause  the 
sound  to  descend  to  the  lower  strata  of  air  full  of 
poison ;  never  will  its  nature  consent  to  such  unreason- 
able demands ;  no,  it  will,  like  a  bird  leaving  its  open 
cage  to  seek  its  liberty,  pass  the  outlines  of  the  sound- 


14  ACOUSTICS. 

ing-board  to  rise  to  a  higher  sphere,  in  the  very  reverse 
direction  to  that  desired.  Forget  not  that  sound  is  of  a 
nobler  character  than  generally  supposed ;  its  require- 
ments are  a  distinguished  treatment,  and  it  will  resist 
every  infringement  upon  its  dignity,  and  hence,  not 
only  through  science,  but  even  art,  is  an  approach  for 
hearing  possible. 

In  my  own  experience  at  several  of  the  public  build- 
ings in  this  city  which  were  erected  under  my  superin- 
tendence, for  example  the  old  Academy  of  Music  in  Four- 
teenth street,  a  building  of  more  capacity  than  any  of 
modern  times,  sound  proved  to  be  excellent.  In  another 
public  building,  where  the  ventilating  apparatus  was, 
in  the  hurry  of  opening  the  building  for  the  first  night, 
neglected,  in  fact  entirely  forgotten,  all  the  ingress  and 
egress  of  air  was  hermetically  closed ;  the  house  was 
crowded  to  excess,  and  the  heat  and  bad  air  accumu- 
lated so  much  that  the  sound  became  perfectly  unintel- 
ligible. I  noticed  the  effect,  and  in  half  an  hour  after 
the  apparatus  was  in  action,  the  sound  became  per- 
fectly clear  and  distinct. 

Many  illustrations  and  examples  to  prove  the  bad 
state  of  air  existing  in  most  of  our  public  buildings 
might  be  introduced,  and  its  effect  upon  sound,  but  I 
think  it  better  to  pass  over  them  ;  however,  I  will  take 
the  liberty  of  saying  a  few  words,  and  will  point  out 
the  causes  why  the  Hall  of  Eepresentatives  and  the 
Senate  Chamber  in  the  Capitol  at  Washington  are  any- 
thing but  desirable  for  the  purpose  of  good  hearing. 
Each  of  these  halls  is  of  an  oblong  form,  the  galleries 


ACOCSTICS.  15 

project  from  the  enclosing  walls  inwardly  on  all  sides, 
and  are  of  considerable  depth  enclosed  underneath. 
Each  hall  has  a  large  skylight  corresponding  with  the 
form  of  the  hall ;  in  such  the  light  is  not  direct,  but 
only  a  reflected  light,  and  in  gloomy  days  hardly  suffi- 
cient, rather  dull ;  the  Speaker's  desk  is  placed  on  the 
longitudinal  side  of  the  hall,  and  the  lower  seats  radi- 
ating in  a  circle  towards  the  Speaker's  desk.  In  the 
lower  part  of  the  hall's  enclosed  by  the  galleries,  the 
contracted  space  naturally  assists  sound,  the  air  being 
more  condensed;  but  ventilation  is  insufficient,  and  tho 
lower  columns  of  air  being  heavy,  the  sound  rises  above 
the  galleries  to  the  more  open  space  above.  If  the 
two  halls  were  calculated  to  be  occupied  for  only  a 
few  hours'  time,  and  well  ventilated,  it  might  answer 
very  well ;  but  being  occupied  the  whole  day  and  often 
crowded,  the  quantity  of  air  contained  in  the  whole 
space  is  insufficient,  and  as  the  ceilings  are  too  low 
above  the  galleries,  the  strata  of  air  become  very  of- 
fensive, and  with  the  dim  light  through  the  skylights 
you  will  find  those  halls  anything  but  pleasant ;  that 
the  elastic  vitality  requisite  to  clear  reflection  of  mind 
and  sound  is  impaired,  and  that  the  bodies  become 
feverish,  nervous  and  restless,  none  of  the  Senators  and 
Congressmen  will  deny.  The  exclusion  of  a  direct 
light,  which  always  gives  life  and  elasticity  to  a  conge- 
nial air  for  sound  and  health,  aside  from  the  effect  of  a 
poisoned  air,  was  a  great  mistake.  If  these  halls  were 
better  ventilated,  with  the  light  as  it  is,  they  would  bo 
excellent  for  fattening  purposes,  but  ruin  to  the  liver. 


16  ACOUSTICS. 

In  regard  to  the  form  of  these  halls,  I  will  refer  here- 
after. Strong  lighted  halls  will  always  be  best  for 
sound,  as  light  is  part  of  ventilation  and  adds  great 
elasticity  to  the  air. 

The  sun,  our  great  benefactor,  supplies  us  with  heat 
and  light ;  the  whole  day  long  we  enjoy  this  blessing 
direct,  and  through  this  influence  the  night  air  remains 
healthy.  Now  imagine  a  locality  like  the  Senate  Cham- 
ber and  Hall  of  Representatives,  insufficient  in  venti- 
lation, insufficient  in  the  quantity  of  air,  and  in  the 
exclusion  all  day  of  direct  light ;  could  the  result  be 
expected  otherwise  ?  I  will  introduce  here  another 
example  to  prove  the  correctness  of  my  assertions. 
You  will  sometimes  find  theatres,  churches,  etc.,  with 
tolerably  intelligible  sound  without  much  ventilation, 
and  how  is  this  possible  ?  Then  mark,  in  all  those 
cases  you  will  find  more  air  than  is  requisite  for 
breathing,  and  consequently  it  takes  longer  time  to 
affect  the  air  with  poison,  or  the  house  is  only  partly 
filled,  a  circumstance  which  assists  much  ;  but  to  as- 
sist sound  by  increasing  the  volume  of  air  more  than 
necessary  would  be  an  expensive  operation,  and  then 
it  would  only  be  one-sided,  and  would  to  a  certain  ex- 
tent put  a  restriction  upon  the  use  of  the  house. 

This  theory  will  lead  to  innumerable  changes  if 
properly  followed ;  it  will  infuse  fresh  air  into  the  lungs, 
and  add  to  health ;  it  will  arouse  the  stupor  of  the 
audience,  caused  by  poisoned  air ;  it  will  assist  elo- 
quence and  strength  of  voice ;  it  will  assist  sound 
reasoning,  and  it  will  assist  to  elevate  the  mind. 


ACOUSTICS.  17 

not  this  theory  benefit  multitudes  of  hearers  who  now, 
in  thousands  of  cases,  go  home  dissatisfied  with  the 
loss  not  only  of  their  time,  but,  with  it,  the  loss  of 
knowledge,  as  it  was  impossible  to  hear,  and  the  op- 
portunity for  gaining  which  may  never  return?  A  stamp 
will  be  placed  upon  future  temples  of  a  true  character, 
which  will  allow  thousands  of  people  to  assemble, 
and  afford  a  more  extensive  diffusion  of  knowledge, 
the  want  of  which  now  is  so  keenly  felt. 

SIZE    AND    FORM    OF    PUBLIC    HALLS. 

Now  I  will  turn  to  the  details  of  size,  form,  ma- 
terials, and  art,  to  show  how  necessary  these  attributes 
are  to  assist  sound,  even  in  all  its  full  vigor  of  life. 
Sound  must  have  no  obstacles ;  its  nature  is  disturbed 
almost  like  the  sharp  edge  of  a  razor;  no  matter  how 
perfect  the  steel  may  be  its  nature  is  the  same,  that  of 
the  most  refined  kind,  the  most  susceptible  of  any  in* 
harmonious  infringement. 

No  doubt  every  reader  will  admit  that  a  certain  ex- 
tent of  space  is  necessary  for  the  diffusion  of  sound  ; 
if  the  space  is  too  large  the  sound  will  exhaust  itself  at 
a  certain  distance  ;  this  fact  proves  itself  almost  daily. 
Many  experiments  prove  that  in  theatres  the  sound 
from  a  clear  speaking  voice  is  distinctly  heard  to  a 
distance  of  80  feet  in  front ;  but  this  is  a  maximum  not 
to  be  overstepped ;  in  the  direction  of  60  feet  on  each 
side,  and  in  the  rear,  of  40  or  50  feet.  This  proportion 
of  figures  will  lead  at  once  to  the  conclusion  that  the 


18  ACOUSTICS. 

best  form  for  sound  or  distinct  hearing  will  confine 
itself  to  the  circle  or  egg-lines  ;  the  extent,  however,  of 
distinct  sound  in  buildings,  other  than  theatres,  where 
the  arrangements  of  seats  and  form  are  different,  may 
even  reach  the  distance  of  150  feet  in  front,  on  each 
side  80  feet,  and  60  feet  towards  the  rear,  and  even 
more.  The  first  named  figures,  as  I  stated  before,  led 
to  a  circle  with  the  central  point  20  feet  from  the 
speaker,  or  to,  a  form  approaching  an  ellipsis. 

The  three-quarter  circle  form  has  proved  itself  the 
best  so  far  in  a  theatre ;  but  still  improvements  might 
be  made  even  in  this  form.  The  three-quarter  circle 
lines  near  the  ends  are  not  calculated  to  contract  the 
sound  in  its  forward  march  sufficiently,  and  a  funnel- 
like  direction  of  the  side  lines,  starting  from  the  pro- 
scenium in  an  oblique  direction  to  the  right  and  left, 
inclosing  the  lines  with  a  circle,  would  surely  assist  the 
force  of  sound  in  its  forward  course ;  this  arrangement 
would  allow  many  additional  seats,  would  not  only 
assist  decoration,  but  even  construction  and  save  ex- 
pense. Without  doubt  the  best  and  most  practical 
method  to  strengthen  sound  in  any  building  calculated 
for  hearing,  is  to  break  the  same  in  such  -a  manner  as 
to  facilitate  its  natural  course  from  its  original  starting- 
point  toward  the  hearers,  with  due  regard  to  the 
natural  and  reflecting  or  broken  sound,  producing  dif- 
ferences in  time,  which  would  lead  to  confusion  rather 
than  strength,  and  to  avoid  this  evil  all  walls  or  objects 
calculated  to  confine  or  break  sound  should  not  be  too 
far  distant  from  the  place  of  the  speaker. 


ACOUSTICS.  19 

The  form  of  the  ancient  theatres,  the  semicircular 
form,  has  been  found  altogether  impractical  for  modern 
stage  arrangements,  and  insufficient  for  a  large  number 
of  seats,  the  most  important  demand  of  the  present 
day.  The  forms  of  the  newer  times  which  have  been 
recommended  and  which  have  been  executed  are  the 
following : 

1.  An  oblong,  closing  with  a  semicircle  at  the  end. 

2.  The  semi-elliptical  form. 

3.  A  part  of  a  circle  larger  than  one-half,  or  semi- 
circle. 

All  these  halls  may  have  galleries,  one  above  the 
other  in  similar  outside  lines,  and  should  in  all  cases, 
except  in  very  small  buildings,  descend  towards  the 
proscenium.  In  the  old  Academy  of  Music,  the  gal- 
leries descended  8  feet  from  the  middle  opposite  the 
stage  towards  the  proscenium.  This  mode  of  construc- 
tion allows  better  sight,  and  more  seats  are  gained ; 
another  advantage  is,  the  sound  reaches  directly  to 
every  spot  without  interruption,  and  it  gives  an  in- 
creased perspective  effect,  which  adds  to  the  splendor 
of  the  building,  and,  in  fact,  transforms  a  theatre  to  a 
most  cosy  place.  This  arrangement  should  never  be 
neglected,  especially  for  opera  houses,  where  most  of 
the  visitors  desire  to  be  seen  in  their  costly  attires,  as 
well  as  to  see.  In  planning  the  old  Academy  of  Music 
I  was  forced  to  this  arrangement,  viz. :  the  descent  of 
the  galleries,  as  the  number  of  seats  required  was 
5,500,  and  without  it  many  hundreds  of  seats  would 


20  ACOUSTICS. 

have  been  useless.  This  immense  descent  of  8  feet, 
never  known  or  executed  in  any  other  theatre  before, 
was  one  of  the  main  causes  of  the  success  of  acoustics 
in  that  house ;  the  great  number  of  seats  in  the  gal- 
leries, seven  and  eight  rows  in  depth  on  the  side  alone, 
demanded  a  great  height  of  the  building ;  78  feet  was 
the  height  from  the  middle  of  parquet  floor  to  the  ceil- 
ing, and  this  space  gave  such  a  volume  of  condensed 
air  that,  without  ventilation  even,  it  would  have  secured 
at  least  for  two  hours'  time  a  healthy  and  congenial  air 
for  sound ;  but  here  I  will  add  that  all  the  walls,  ceil- 
ings, gallery- breast  works,  etc.,  throughout  the  house 
were  covered  with  boards  tongued  and  grooved  so  that 
every  part  formed  a  sound-board.  The  shape  of  the 
auditorium  ceiling  formed  part  of  a  circle,  its  centre 
point  about  4  feet  below  the  parquet  floor ;  this  form 
is  necessary  to  prevent  the  rays  of  sound  from  concen- 
trating more  toward  the  middle  of  the  building  than 
toward  the  side  walls.  The  outlines  of  the  auditorium 
of  the  old  Academy  approached  more  the  shape  of  a 
funnel  with  a  semicircle  at  the  end;  the  proportion  of 
the  auditorium  was  beyond  any  approach  to  known 
forms,  the  depth  being  about  one-third  more  than  the 
width;  a  deep  proscenium  suggested  itself  to  lessen 
the  proportion,  and  this  very  depth  of  the  proscenium 
proved  most  excellent  for  propelling  sound,  as  the  air 
in  the  direct  neighborhood  of  the  originating  point  of 
sound  became  more  dense,  besides  allowing  a  decora- 
tion so  befitting  for  the  frame  which  incased  a  living 
and  most  attractive  picture. 


ACOUSTICS.  21 

I  will,  however,  return  again  to  the  forms  of  theatres 
in  use  before  mentioned.  The  oblong  form,  with  a 
closing  semicircle  at  the  end,  has  many  advantages ; 
it  allows  a  plain  construction  and  many  seats,  and  in 
it  the  sound  is  clear  from  obstructions,  and  its  action 
is  clear  and  natural,  but  gooci  sight  could  only  be  gain- 
ed by  terracing  the  seats  towards  the  proscenium,  which 
would  be  unpractical  for  proper  decoration,  and  would 
leave  many  seats  near  the  proscenium  useless.  Three 
theatres  only  in  Europe  have  come  under  my  observa- 
tion ;  one  in  France,  one  in  London,  and  one  at  Mann- 
heim in  Germany.  To  retain  somewhat  the  advantages 
of  the  oblong  form,  the  elliptical  was  substituted,  with 
a  partial  success ;  better  seats  near  the  proscenium 
were  gained  in  comparison  with  the  oblong.  Dumont 
and  Langhouse  have  written  on  this  subject,  and 
especially  Mr.  Langhouse,  the  architect  of  the  Berlin 
Opera  House,  in  his  work  considers  the  elliptical  form 
as  the  best ;  he  sets  forth  many  advantages  :  "  He  says 
there  is  no  echo  possible,  and  all  the  circular  or  rota- 
tory movements  vanish."  (Echoes  are  only  dangerous 
in  very  large  spaces ;  but  more  on  this  subject  here- 
after.) 

He  states  further :  "  If  the  speaker  places  himself 
on  one  of  the  centre  points,  or  nearly  so,  the  rays  of 
sound  reflect  only  once,  and  unite  in  concentrating 
at  the  other  centre  points  without  causing  any  con* 
fusion." 

"  Stiller,"  the  great  Prussian  architect,  sets  forth  his 
objections  to  this  form,  and  says  : 


22  ACOUSTICS. 

1.  "  The  distance  of  the  hearers  from  the  point  of 
the  speaker  differs  so  much  that  an  unequal  arrival  of 
the  sound  rays  is  the  consequence." 

2.  "  The  rays  of  sound  will  not  be  likely  ever  to  bo 
forwarded  from  one  of  the  centres  to  concentrate  and 
unite  at  the  other  centres  all  at  the  same  time ;  on  the 
contrary,  many  concentrating  intermixing  rotary  move- 
ments will  be  produced,  and  he  points  oiTt,  that,  after 
all,  the  concentrating  points  for  the  rays  are  at  the  mid- 
dle, and  adds,  that  in  this  very  locality  confusion  takes 
place,  or  at  least  where  the  harmonious    fulness  of 
sound  is  lost,  and  gives  as  an  example  the  Opera  House 
in  Berlin." 

To  avoid  all  those  difficulties,  parts  of  the  circular 
form  were  substituted  till  they  reach  the  three-quarter 
circle. 

As  I  stated  before,  the  semicircle,  aside  from  the 
disadvantage  of  not  allowing  many  seats,  prevents  a 
good  connection  with  the  proscenium. 

The  circular  or  rotary  movements,  which  take  place 
in  a  full  circle,  are  in  a  three-quarter  circle  somewhat 
avoided,  the  proscenium  placing  a  barrier  in  its  way; 
and  here  it  is  to  be  added,  that  a  large  number  of  sound 
rays  will  extend  to  the  stage  and  lose  their  strength  by 
striking  the  flats  which  do  not  reflect,  and  no  resound- 
ing or  echo  is  possible;  the  partitions  also  in  the  gal- 
leries for  the  divisions  of  private  boxes  hinder  the 
rotary  movements.  It  is  true  there  are  even  in  the 
three-quarter  circle  rotatory  movements,  but  they  do 
not  amount  to  any  serious  obstacle.  The  views  of 


ACOUSTICS  23 

architects  generally  to  remedy  the  evils  of  the  before 
mentioned  forms  were  manifold.  I  will  here  state  a 
few  more,  merely  for  the  sake  of  example  and  for  the 
purpose  of  proving  that  after  all  these  experiments, 
which  were  very  good  and  laudable  in  themselves,  the 
results  were  one-sided  only.  One  of  the  many  methods 
to  assist  sound  was,  to  construct  flues  with  openings,  on 
the  principal  galleries  opposite  the  stage,  extending 
above  the  roofs  like  chimney  flues  to  create  a  draft, 
but  this  proved  a  failure  ;  too  much  draft  in  those  flues 
inconvenienced  the  hearers,  and  as  the  forward  move- 
ment oi  sound  is  much  swifter  than  the  draft  in  the 
flues,  the  desired  effect  was  lost.  Another  proposition 
was  introduced  to  assist  sound,  and  to  prevent  the 
rotary  movement  by  constructing  semicircular  pro- 
jections like  bay  windows,  in  front  of  every  private  box, 
and  this  is  reported  to  have  done  some  good ;  another 
proposed  method  is,  to  cover  all  the  boxes  with  drapery, 
which  deadens  the  sound  completely,  an  evil  worse 
than  the  one  to  be  superseded.  A  great  evil  caused 
by  the  construction  of  galleries,  should  be  mentioned 
and  noticed ;  here,  in  some  American  theatres,  the  gal- 
leries are  very  deep,  in  order  to  allow  many  rows  of 
seats ;  the  projections  of  those  galleries  opposite  the 
stage  are  often  so  large  that  they  almost  reach  the 
middle  of  the  auditorium,  and  the  height  from  the  floor 
to  the  lower  front  line  of  gallery  breastwork  or  railing 
is  seldom  more  than  ten  feet,  with  a  ceiling  underneath 
running  parallel  with  the  rows  of  seats  somewhat  shed- 
fashion;  this  construction  not  only  prevents  the  sound 


2.1  ACOUSTICS. 

from  entering  direct,  but  gives  under  the  galleries  a 
most  uncongenial  place  for  sight  and  comfort. 

Perhaps  a  retrospective  view  of  all  the  arrangements 
and  evils  connected  with  them,  to  gain  intelligible 
sound,  especially  in  theatres,  here  finds  its  proper 
place,  and  I  will  therefore  proceed  to  explain  'why  all 
of  them  have  only  partially  succeeded.  I  say  partially, 
because  the  results  refer  only  to  form,  size,  and  ma- 
terials employed,  although  combined  they  were  in- 
tended to  promote  good  sound,  and  that  failed.  The 
experiments  individualized  the  attributes  of  sound 
only,  but  the  individuality  of  sound  itself,  its  living  vi- 
tality, its  food,  its  digestive  nature,  was  insultingly 
neglected,  and  its  perplexing,  stubborn,  and  resisting 
power  was  plainly  visible,  and  so  sound  became  a  sub- 
ject looked  upon  as  very  fickle,  unreliable,  expensive, 
and  even  dangerous  to  be  dealt  with,  and  fell  into  ob- 
livion; but  this  status  quo  cannot  last,  this  is  sure  !  so 
let  us  take  it  up  again  and  try  if  we  cannot  push  it 
forward,  out  of  its  stupor  to  its  proper  light,  and  instal 
it  into  that  high  sphere  to  which  it  belongs,  and  where 
it  can  shine  as  one  of  those  millions  of  examples  of 
God's  wisdom  in  his  beautiful  and  harmonious  dictates 
of  nature,  wliich  are  all  to  our  benefit  and  blessing. 

The  human  body,  the  lungs,  etc.,  cannot  exist  with- 
out air,  and  so  the  voice,  which  originates  from  the 
body  through  air,  which  lives  in  air,  operates  in  air  and 
loses  its  vitality  without  it,  should  naturally  lead  us  to 
the  conclusion  that  sound  can  only  be  useful  in  a 
proper  and  healthy  air,  to  such  an  extent  as  we  require; 


ACOUSTICS  25 

and  it  appears  that  the  same  influences  of  impure  air 
acting  upon  our  feeling  through  our  body  are  precisely 
the  same  influences  which  sound  has  to  encounter.  We 
often  hear  people  say :  I  have  made  it  a  rule  not  to 
visit  a  business  man  on  a  rainy  day  on  business 
of  importance,  as  on  such  a  day  his  mind  is  af- 
fected ;  he  has  not  the  elasticity  of  mind  to  enter  into 
a  heavy  business  transaction  ;  and  do  you  not  find  on 
a  rainy  day  that  the  bells  lose  their  distinct  sound,  and 
even  the  rattling  of  carriages  and  carts  passing  in  the 
streets  is  of  less  noise?  don't  you  feel  gloomy  yourself 
on  all  such  days,  and  restless  ?  do  you  not  notice  what 
a  difference  presents  itself  when  you  rise  early  in  the 
morning  and  inhale  a  clear,  fresh  air,  which  gives  you 
an  elasticity  mentally  and  physically?  Ask  the  musician 
whether  he  does  not  notice  a  change  in  tone  by  such 
influences  in  the  atmosphere ;  ask  men  of  science  who 
make  sound  their  special  interest  and  digest  over  it, 
and  examine  its  characteristics  still  more  exhaustively, 
and  you  will  come  to  the  same  theory  which  I  have  in- 
troduced, based  upon  my  own  past  experience  and  as- 
sisted by  inductive  reasoning  between  known  facts  and 
phenomena  and  the  laws  or  principles  which  govern 
them. 

The  number  of  illustrations  I  introduced  at  the  be- 
ginning showed  the  effects  of  the  atmosphere  upon 
sound,  but  keep  in  mind  that  the  atmosphere  which 
surrounds  us  in  public  buildings  differs  from  the  com- 
bined atmosphere  of  that  grand  space  between  hea\en 
and  earth  ;  this  mistake  has  misled  many  architects  in 


26  ACOUSTICS. 

their  constructions,  and  to  most  ruinous  results ;  yes, 
I  know  of  one  large  church,  costing  one  million  and 
a  half  dollars,  which  proved  to  be  entirely  unfit  for 
use,  and  remains  so  up  to  this  time.  In  this  case  the 
architect  took  it  for  granted  that  a  cannon  fired  in  a 
valley  could  not  be  heard  on  a  high  mountain,  and 
vice  versa,  and  he  built  a  large  cupola  of  great  height, 
forming  the  main  body  of  the  church,  supposing  that 
the  sound  would  not  rise  over  60  feet  above  the 
floor,  a  rule  often  introduced,  but  not  applicable  to  the 
atmosphere  contained  inside  of  buildings,  and  there- 
fore took  it  for  granted  that  the  cupola  above  the  60 
feet  could  not  be  reached,  and  prevent  the  forward 
march  of  the  sound ;  but  the  very  reverse  result  was 
noticed.  With  no  ventilation  to  regulate  the  different 
strata  of  air,  the  sound  rushed  up  to  the  cupola  in 
force,  finding  the  lower  strata  of  air  heavy,  causing 
a  rotary  circular  movement  of  the  rays,  and,  partially 
returning  in  a  state  of  confusion,  became  wholly  unin- 
telligible. 

The  atmosphere  in  public  buildings  cannot  be  the 
same  as  the  outer  combined  atmosphere.  Why,  the 
very  fact  that  we  are  living  in  the  lower  strata  of  the 
atmosphere  proves  it,  and  hence  it  follows  that  we 
have  in  our  buildings  the  lower  strata  of  air  in  what- 
ever condition  we  find  them,  in  their  natural  state,  but 
condensed  ;  we  often  find  them  damp,  heavy,  cold,  and, 
with  too  little  ventilation,  overheated.  In  public  build- 
ings we  have  only  one  atmosphere  to  battle  with,  for 
our  purpose  a  very  lucky  circumstance.  Only  imag- 


ACOUSTICS.  27 

ine,  if  the  inner  atmosphere  in  a  building  wers  exposed 
as  much  as  the  outer,  the  sound  would  be  very  often 
in  the  most  intense  state  of  excitement,  and  it  would 
be  impossible  to  arrive  at  means  to  prevent  it.  See  how 
thoroughly  that  immense  space  between  heaven  and 
earth  filled  with  air  is  ventilated ;  to  go  into  details 
and  to  understand  them  perfectly,  would  require  the 
knowledge  or  theory  of  the  wind,  the  evaporation  pro- 
cess of  the  earth  to  produce  clouds  in  order  to  replen- 
ish the  earth  for  the  loss  sustained  by  the  sun,  etc. ; 
look  at  the  daily  changes  of  temperature,  yes  even 
hourly,  the  different  seasons  of  the  year,  what  does  all 
this  mean?  Why,  ventilation,  to  give  a  healthy  inhal- 
ing air  to  the  living,  and  by  the  living  I  mean  all  ob- 
jects we  see,  that  are  full  of  life. 

Now  let  us  see  what  we  have  done  with  this  single 
stratum  of  air,  a  distinct  atmosphere  which  is  left  for 
our  buildings  ;  why,  we  have  done  almost  nothing,  we 
have  not  supplied  it  with  sufficient  fresh  air,  we  have 
not  regulated  the  different  strata  of  air,  we  have  not 
stopped  the  influence  of  the  poison  produced  by  the 
exhaled  air,  and  left  it  often  to  the  tender  mercy  of 
materials,  which  become  dangerous  by  the  neglect  of 
this  impure  state,  and  these  neglects  have  to  be  avoid- 
ed, or  we  can  not  succeed.  Nature  has  helped  us  much, 
she  has  given  us  a  condensed  atmosphere  entirely  clear 
of  outside  influences,  and  this  alone  should  be  an  in- 
ducement to  relieve  the  evils  mentioned,  to  prevent 
that  cankerous  odor  of  a  stagnant  atmosphere.  Let  us 
trace  now  how  an  impure  air  operates  on  the  reflec- 


28  ACOUSTICS. 

tion  of  sound,  and  how  all  those  movements  so  danger- 
ous to  intelligible  sound  have  been  produced. 

In  almost  all  cases  in  the  present  state  of  the  at- 
mosphere in  our  public  buildings  without  proper  ven- 
tilation, the  reflection  of  sound  becomes  confused  by 
obstructions  and  angular  forms  in  its  march  ;  but  the 
main  cause  of  this  annoying  result  originates  more  in 
the  different  strata  of  air,  part  of  them  being  satura- 
ted with  matter  which  is  heterogene  to  the  distribution 
of  sound  throughout,  and  which  confines  the  sound  to 
certain  strata  only ;  and  as  the  heterogene  strata  al- 
ways form  their  layers  at  the  lower  part  of  the  atmos- 
phere, saturated  by  the  exhaled  air,  and  of  a  greater 
specific  weight  than  the  others,  a  distinct  division  of 
.the  upper  from  the  lower  is  formed,  and  the  upper,  as 
likewise  the  lower  strata  become  condensed.  This  con- 
densation in  one  sense  should  assist  sound,  and  does 
so  in  all  strata  where  the  greatest  purity  of  air  exists, 
whereas  in  those  strata  saturated  with  impure  air,  the 
condensation  actually  stops  the  sound,  and  it  becomes 
unintelligible  to  a  certain  degree,  and  in  proportion  to 
the  volume  of  condensed  impure  air.  This  proves  that 
the  inner  atmosphere  of  a  public  building  under  the 
influence  of  exhaled  air,  undergoes  two  processes  of 
condensation, — the  first  one  by  the  inclosure  of  the  in- 
ner atmosphere  cleared  of  the  outer  influences,  and 
the  second  by  the  exhaled  air  of  the  human  body, 
which  becomes  heavier,  and  through  its  weight  the 
second  process  of  condensing  the  inner  air  takes  place, 
and  this  second  process  of  condensation  is  the  most 


ACOUSTICS.  29 

ruinous  process  to  hinder  distinct  sound,  especially  in 
those  places  where  the  sound  is  most  needed.  The 
sound  diffuses  its  rays  immediately  to  all  particles  of 
the  air,  from  its  originating  point  of  contact,  provided 
the  air  is  congenial  ;  but  the  moment  the  rays  find  ob- 
structions of  a  serious  nature,  they  rise  to  other  parts 
with  more  propelling  power ;  gliding  over  J,  even  J  of 
the  volume  of  air  contained  in  the  building  with  con- 
tempt, and  proceeding  to  the  other  part,  they  commence 
playful  and  vexatious  tricks  by  rotary  movements,  by 
rotary  concentrations,  by  resoundings,  etc.,  and  leave 
the  audience  in  perplexity ;  such  phenomena  you  will 
find  in  very  large  buildings,  where  you  would  suppose 
that  the  rays  of  sound,  deprived  of  J  and  even  of  more 
of  the  volume  of  the  inner  atmosphere,  find  ample  field 
for  action. 

Echoes  are  never  found  in  smaller  rooms,  but  when 
a  sufficient  interval  exists  between  a  direct  and  a  re- 
flecting sound  we  hear  the  latter  as  an  echo.  "  The 
reflected  sound  moves  with  the  same  velocity  as  the 
direct  sound,  so  that  in  air  of  a  freezing  temperature 
the  echo  of  a  pistol  shot  from  the  face  of  a  cliff  1,090 
feet  distant  is  heard  two  seconds  after  the  explosion." 

"  In  large  furnished  rooms,  the  reflection  of  sound 
sometimes  produces  very  curious  effects.  Standing, 
for  example,  in  the  gallery  of  the  Bourse,  at  Paris,  you 
hear  the  confused  vociferation  of  the  excited  multitude 
below.  You  see  all  the  motions  of  their  lips,  as  well 
as  of  their  hands  and  arms.  Yon  know  they  are  speak- 
ing— often,  indeed,  with  vehemence,  but  what  they  say 


30  ACOUSTICS. 

you  know  not.  The  voices  mix  with  their  echoes  into 
a  chaos  of  noise  out  of  which  no  intelligible  utterance 
can  emerge.  The  echoes  of  a  room  are  materially 
damped  by  its  furniture." 

The  presence  of  an  audience  may  also  render  intel- 
ligible speech  possible,  where  without  an  audience  the 
definition  of  a  direct  voice  is  destroyed  by  its  echoes. 

Sounds  are  also  reflected  by  the  clouds. 

"  When  the  sky  is  clear,  the  report  of  a  cannon  on  an 
open  plain  is  short  and  sharp,  while  a  cloud  is  suffi- 
cient to  produce  an  echo  like  the  rolling  of  distant 
thunder.  A  feeble  echo  also  occurs  when  sound  pass- 
es from  one  mass  of  air  to  another  of  different  density. 
Thus  by  day  the  sound  has  to  pass  through  an  atmos- 
phere which  frequently  changes  its  density."  Again 
I  introduced  a  number  of  observations  taken  from 
English  and  German  works,  generally  known,  and  find 
them  corresponding  in  every  respect.  My  intention  is 
to  introduce  as  many  examples  as  possible,  so  that  a 
more  comprehensive  view  may  be  gained,  especially  by 
those  who  are  less  acquainted  with  this  subject.  The 
cause  of  echoes  is  here  given,  but  it  must  be  added 
that  the  sound  will  not  reflect  so  intensely  to  repro- 
duce distinctness  unless  the  form  is  of  a  peculiar  na- 
ture to  assist ;  this  you  will  notice  not  alone  in  the 
outer  atmosphere,  but  also  in  the  inner,  or  in  very 
large  buildings,  where  the  sound  rays,  owing  to  their 
direction  of  contact  in  sharp  angles,  •  reflact  OIICG  or 
twice,  causing  a  resonance,  and  returning  in  this  con- 
dition to  the  ear.  In  a  Merchants'  Exchange,  or  in 


ACOUSTICS.  31 

any  ball  where  hundreds  of  people  are  assembled,  and 
where  each  desires  his  voice  to  be  heard,  confusion  of 
sound  must  take  place,  as  the  sound  rays  sent  forward 
by  each  individual  in  different  directions,  fill  the  air 
with  them,  intermixed,  and  sometimes  to  such  an  ex- 
tent that  it  is  impossible  for  a  person  to  hear  his  own 
voice.  One  of  these  examples  is  found  in  the  lower 
part  of  this  city.  In  such  cases  it  is  difficult  to  reme- 
dy the  evil  altogether,  because  the  atmosphere  is  over- 
taxed ;  it  takes  the  place  of  a  servant  who  cannot  serve 
two  masters,  and  who  recoils  quickly  at  the  imposition. 
But  what  can  be  done  for  a  remedy  ?  First  ventilate 
well,  then  cover  the  walls  with  drapery  to  deaden  the 
sound,  especially  when  the  room  is  not  in  proper  pro- 
portion to  its  height  ;  the  third  movement  is  to  divide 
the  ceiling  by  deep  sunk  panels ;  if  too  late,  divide  the 
ceiling  longitudinally  and  transversely  by  sheets  of 
canvas  not  less  than  3  feet  in  depth  from  the  ceiling, 
which  may  be  done  with  colored  flags,  forming  some- 
what of  a  decoration.  Ventilation  will  prevent  the  ac- 
cumulation of  different  masses  of  condensed  air  which 
in  themselves  would  produce  echoes,  in  many  cases, 
the  quantity  of  air  not  being  sufficient  for  the  number 
of  people  assembled.  In  smaller  rooms  like  court- 
rooms, where  only  one  voice  is  heard,  a  deep  panelled 
ceiling  would  be  injurious ;  if  you  wish  to  convince 
yourself  of  this,  visit  the  old  court-rooms  near  the  New 
Court  House,  in  the  lower  part  of  this  city.  It  was 
stated  before  that  an  audience  may  also  render  intel- 
ligible speech  possible  where,  without  an  audience,  the 


32  ACOUSTICS. 

definition  of  a  direct  voice  is  destroyed  by  its  echoes. 
This  is  true,  and  may  be  accounted  for  by  two  distinct 
causes  ;  the  first  is,  viz.:  by  the  presence  of  an  audi- 
ence the  sound  loses  its  aptitude  to  echoes,  particular- 
ly if  the  audience  is  distributed  over  all  parts  of  the 
house  by  galleries.  The  next  cause  is  :  the  sound  rays 
are  intercepted  in  their  forward  movement,  and  vice 
versa  in  their  return.  In  public  buildings,  or  localities 
where  the  echoes  are  remarkably  distinct,  you  may 
rely  on  it  that  the  construction,  the  proportions,  the 
form,  and  size  is  anything  but  suitable  to  the  propaga- 
tion of  good  and  intelligible  sound,  and  this  proves  the 
larger  the  area  of  an  atmosphere  the  greater  calcula- 
tion and  knowledge  of  sound  is  required. 

It  cannot  be  denied  that  the  use  of  proper  materials 
in  the  construction  of  public  buildings  forms  an  impor- 
tant attribute  to  the  propagation  of  distinct  sound,  or 
at  least  to  assist  sound.  If  we  examine  musical  in- 
struments, we  find  that  wood  forms  the  best  material ; 
the  thinner  the  sheets  of  wood  used  the  more  elasticity 
they  gain,  and  the  more  susceptible  they  are  to  the 
rays  of  sound.  The  sound  rays  in  their  forward  course 
through  the  air  are  assisted  by  its  elasticity,  and  the 
moment  they  come  in  contact  with  the  thin  .sheet  of 
wooden  wall  they  are  restrained,  but  not  suddenly  or 
abruptly,  as  they  find  still  an  elasticity  to  work  upon. 
The  sound  rays  seem  to  be  pleased  with  the  natural, 
easy,  and  accommodating  restriction;  and  especially  in 
public  buildings,  theatres,  etc.,  where  the  walls  and 
ceilings  are  inclosed  with  boards,  the  sound  seems 


ACOUSTICS.  33 

gratified  to  be  restricted,  conscious  of  its  ability  to  go 
so  far  and  no  farther,  to  apply  its  force,  and  suddenly 
appear  with  a  round,  harmonious,  clear  and  strong 
tone.  But  only  then  is  it  possible  to  produce  this 
strength  and  clearness  when  there  has  been  no  ob- 
struction to  the  sound  rays,  and  only  through  ventila- 
tion is  it  possible. 

In  England  several  trials  have  been  made  with  vari- 
ous materials  ;  for  example,  metal  plates  were  put  up 
to  gain  a  sharp,  penetrating  tone,  especially  for  speak- 
ing purposes,  from  the  absence  of  elasticity  being 
known  ;  but  the  result  could  not  be  expected  to  be 
favorable  without  the  air  being  first  cleared  of  all 
obstructions ;  and  even  had  the  sound  gained  the 
sharp,  penetrating  tone,  it  certainly  would  not  have 
been  desirable  any  more  than  that  emanating  from  an 
empty  bowl  or  hollow  pot.  Notice  the  sharp,  shrill 
tone  of  some  of  our  clergymen  in  the  pulpit,  and 
actors  on  the  stage,  how  disagreeable  it  appears,  and 
with  the  addition  of  the  sharp,  trumpet-like  tone  of  a 
metal  plate  would  it  not  be  shocking  ?  and  I  am  bold 
to  say,  the  sound  rays  would  become  a  fearful  chaos, 
and  scare  the  audience  to  a  quick  exit.  But  wood  we 
cannot  always  use  for  such  a  purpose,  as  the  security 
of  the  building  demands  otherwise,  and  therefore 
hollow  walls,  either  constructed  of  stud  partitions 
plastered  on  both  sides,  or  formed  by  furring  strips  on 
brick  or  stone  walls,  will  somewhat  assist;  but  it 
should  never  be  forgotten  that  materials  will  only 
assist,  not  originate,  the  desired  effect  upon  sound. 


34:  ACOUSTICS. 

Many  theories  have  been  placed  before  the  public  ; 
twenty  books  on  acoustics  I  had  lying  before  me  at 
the  time  I  was  on  the  point  of  building  the  Academy 
of  Music.  I  felt  that  without  some  knowledge  of 
sound  I  could  not  succeed  ;  and  here  was  to  be  one  of 
the  largest  theatres  ever  built ;  a  failure  in  acoustics 
was  a  failure  in  everything,  so  for  eight  days  and  nights 
I  was  engaged  in  studying  those  books,  and  after  sift- 
ing them  all  I  was  placed  in  the  most  painful  situation ; 
in  fact,  the  nature  of  sound  was  a  mystery  to  me  for 
all  practical  purposes.  In  all  those  books  there  were 
not  two  authors  who  agreed ;  the  very  hobby-horse 
one  rode,  another  tried  to  lame,  or  knocked  under  all 
four  legs ;  all  the  books  proved  a  perfect  mystery  of 
scientific  researches.  Some  of  the  authors  went  so  far 
as  to  prove  the  rotation  and  reflection  of  sound  by 
mathematical  calculation,  and  illustrated  them  with 
thousands  of  lines,  and  with  an  infallibility  perfectly 
perplexing;  and  others,  again,  had  the  audacity  to  con- 
tradict its  truthfulnes,  and  still  not  one  of  those  works 
had  the  merit  of  being  generally  admitted  as  correct. 

I  was  not  aware  that  any  more  books  could  be  found, 
so  my  last  hope  from  that  quarter  vanished,  and  the 
only  alternative  was  to  fall  back  upon  my  own  re- 
sources. I  covered  the  whole  interior  auditorium  with 
boards,  hoping  for  success — and  succeed  I  did  ;  but 
this  success  was  not  from  the  use  of  wood  alone,  it  was 
from  the  immense  inner  atmosphere  and  other  details 
which  I  stated  before.  Several  city  papers  requested 
me,  after  the  completion  of  the  building,  to  publish 


ACOUSTICS.  35 

the  secret  of  my  success  for  the  general  good ;  bufc 
how  could  I  at  that  time,  as  I  knew  not  how  soon  my 
hobby-horse  would  break  down  ?  If  my  new  theory 
proves  correct — and  I  am  convinced  it  will,  although 
it  may  at  first  meet  with  some  doubts — it  will  raise  its 
head  erect  in  the  future  when  this  particular  branch 
of  science,  ventilation,  shall  reach  its  culminating  point; 
then  the  atmosphere  will  be  better  understood,  its  im- 
purity, its  outer  influences,  its  quantity  and  quality ; 
then  a  new  field  will  open  itself,  suggestions  will  spring 
into  existence  never  thought  of  before,  and  those  ob- 
jects that  exist  in  air,  that  are  influenced  by  it,  and 
that  cannot  exist  without  it,  will  find  their  proper  at- 
tention, but  not  before !  But  there  is  no  doubt  it  wil- 
be  soon ;  it  is  fortunate  that  ventilation  must  and  will 
become  a  subject  of  great  interest ;  it  has  already  be- 
come so ;  it  is  necessary  for  health,  the  greatest  bless- 
ing we  can  have.  And  why  should  not  ventilation  ba 
introduced  thoroughly  in  public  buildings  ?  And  who 
can  doubt  that  these  sound  rays  would  find  themselves 
at  home;  would  they  not  playfully  enter  into  every 
particle  of  air,  and  joyfully  pay  us  with  a  salute  of  a 
round,  clear,  and  strong  tone,  so  pleasant  to  our  ears  ? 
I  ain  glad  to  state  that  the  principles  of  ventilation 
have  taken  hold  in  our  country,  perhaps  generally 
more  so  than  anywhere  else.  A  new  country  like  ours, 
with  a  population  full  of  energy,  and  minds  devoted  to 
progress,  cannot  fail  to  take  hold  of  rational  ideas  to 
further  their  interests.  Ventilation  would  have  been 
more  extensively  introduced,  had  it  not  been  attempted 


36  ACOUSTICS. 

in  many  cases  more  as  a  means  to  make  money  than 
for  any  practical  purpose,  and  it  lias,  in  consequence, 
lost  many  warm  friends,  and  has  been  actually  an  use- 
less expense  to  hundreds  of  citizens ;  in  many  cases 
worse  than  an  useless  expense — more  the  means  of  de- 
priving them  of  healthy  air  than  if  it  had  been  ignored 
altogether.  This  abuse,  however,  will  rectify  itself 
gradually.  It  is  very  difficult  to  introduce  ventilation 
into  most  of  our  public  buildings,  especially  theatres. 
I  have  had  several  cases  where  I  used  my  best  en- 
deavors to  gain  good  ventilation ;  in  some  cases  thou- 
sands of  dollars  were  expended  for  the  purpose,  and 
what  did  all  my  trouble  amount  to  ?  To  nothing. 
Not  an  inquiry  was  made  how  the  ventilation  was  to 
be  applied.  Lessees  took  charge  of  the  building, 
ventilation  became  a  laughing-stock  to  them ;  more- 
over, it  would  have  required  an  intelligent  person, 
with  an  expense  of  two  or  three  dollars  a  night,  to  take 
charge  and  regulate  it.  But  what  can  be  expected 
from  men  who  become  lessees  of  a  building  for  three 
or  six  months,  with  the  determination,  if  possible,  of 
placing  two  persons  on  one  seat,  without  regard  to 
danger  of  life,  comfort,  or  health  ?  The  condition  of 
sound  is  never  thought  of — on  the  contrary,  they  are 
pleased  for  the  same  audience  to  re-appear  to  hear  the 
other  half  of  the  sentence.  Opposition  is  not  expect- 
ed, as  pretty  nearly  all  theatres  are  alike,  and  con- 
ducted with  similar  management.  I  will  not  say  all, 
but  many  of  them. 


ACOUSTICS.  37 


CHURCHES,    THEIK    FORM,   SIZE,    MATERIALS,    AND    VENTI- 
LATION IN  CONNECTION  WITH  ACOUSTICS. 

It  is  hardly  necessary  to  point  out  the  forms  of 
smaller  churches ;  no  matter  what  they  are,  they  never 
affect  the  sound  very  materially,  unless  they  become  a 
hot-bed  of  bad  air.  The  larger  churches,  which  are 
now  in  demand,  are  the  subject  which  I  wish  to  intro- 
duce to  the  readers,  a  subject  which  must  interest 
them,  as  all  large  churches  in  this  country  have  proved 
failures  in  form  and  acoustics,  to  a  most  lamentable 
loss  to  their  congregations, — one-half  of  the  congrega- 
tion cannot  hear,  and  in  some  cases  the  inner  construc- 
tion is  so  arranged,  as  to  lead  a  person  to  suppose, 
that  the  most  necessary  points,  sight  and  good  hear- 
ing, have  been  studiously  avoided,  in  order  to  intro- 
duce impressions  of  strength,  where  actually  a  very 
small  portion  was  needed,  and  this  arrangement  we  may 
find  in  churches  costing  from  600,000  to  700,000  dol- 
lars .  In  one  large  church  in  this  city  where  you  can- 
not hear,  the  proportion  or  size  would  answer  very 
well,  but  want  of  ventilation  separates  the  aerial  vol- 
ume into  two  distinct  masses,  the  heavier  part  below, 
and  the  more  flexible  above;  and,  in  consequence,  the 
sound  separates  itself  from  the  lower  sphere,  and  rises 
to  the  higher,  precisely  where  it  is  not  wanted,  and 
with  a  strength  causing  reflecting  vibrations  of  a  na- 
ture so  monotonous  as  to  create  a  sleepy  sensation. 
There  are  two  classes  of  large  established  churches, 


38  ACOUSTICS. 

namely,  the  Catholic  and  the  Protestant,  and  each  has 
its  ritual,  and  has  to  be  treated  accordingly. 

At  the  present  time  the  requirements  of  large 
churches  are,  that  they  be  constructed  with  all  possi- 
ble economy  for  good  sight  and  hearing,  and  befitting 
the  house  of  God,  and  that  as  many  people  as  possible 
may  be  seated.  How  far  these  requirements  have 
been  complied  with,  the  many  examples  rather  of  a 
caricature  nature  give  a  true  synopsis  of  the  actual 
state  of  religious  feeling  of  the  present  day.  Every 
public  building  ought  to  be  in  reality  the  pulse  of  the 
inner  life,  and  the  house  of  God  especially  should  not 
only  be  harmonious  in  its  proportions,  but  of  such 
construction  as  to  stamp  it  with  its  true  character  so 
impressive  to  the  mind  of  the  beholder. 

Harmony,  Science,  and  Art  elevate  us  to  a  higher 
sphere  of  life,  and  should  never  be  neglected  in  the 
house  of  God. 

"  Many  suppose  that  the  Protestant  churches  are  to 
be  of  an  entirely  different  type  to  and  in  contrast  with 
Catholic  churches  ;  this  is  a  great  mistake  ;  the  Refor- 
mation has  not  produced  a  new  church — it  has  only 
assumed  to  have  abolished  the  errors  and  abuses  of 
the  Catholic  church,  and  hence  a  new  and  specific 
Protestant  style  would  be  a  folly.  In  this  field  there 
could  be  no  protest,  only  an  acknowledgment  and  a 
necessity  for  reproduction  ;  and  the  best  style  will  be 
the  one  which  has  the  facility  capable  of  entering  into 
the  smallest  details  of  Christian  and  ecclesiastical 
spirit  in  the  execution  of  the  whole  and  in  detail,  with 


ACOUSTICS.  89 

a  steadfast  harmonious  consequence,  and  calculated 
to  represent  a  most  intensive  view."  The  Catholic 
church  presents  daily  the  holy  rite  of  the  Lord's  Sup- 
per, and  every  person  assembled  on  such  occasions 
should  have  the  privilege  of  seeing  every  ceremony  in 
connection  with  it.  The  sermons  which  are  preached 
are  short,  but  from  that  very  shortness  they  should  be 
heard  by  every  one,  and  well  understood.  It  follows 
that  a  concentration  of  seats  is  necessary,  with  a  direct 
sight  of  the  altar ;  this  is  the  principal  requirement,  and 
how  can  it  be  done  ?  The  basilica  is  the  oldest  Chris- 
tian form  of  church,  and  will,  if  rightly  understood, 
answer  the  purpose  best.  It  is  the  most  simple  form, 
less  costly  in  construction,  highly  favorable  for  decora- 
tion, and  its  perspective  may  even  be  extended  to  the 
effect  of  sublimity,  and  will  admit  of  almost  any  style. 
It  is  true,  galleries  placed  longitudinally  in  the 
basilica  form  will  not  be  desirable,  and  they  form  in 
very  large  Catholic  churches  a  serious  obstacle  for  „ 
decoration.  Now  let  us  take  a  space  of  65  feet  in  width 
and  250  feet  in  length  including  the  chancel,  with 
transepts  forming  a  cross  ;  the  number  of  seats  may 
reach  2,800,  each  with  a  clear  unobstructed  view  of  the 
altar.  The  next  demand  is  to  supply  a  number  of 
side  altars,  perfectly  independent,  with  a  separate  pas- 
sage. This  demand  is  met  by  placing  the  side  altars 
on  the  longitudinal  walls  inclosing  the  side  aisles,  with 
10  feet  for  the  altar,  and  a  passage  of  16  or  18  feet  in 
width,  say  28  feet  in  all  will  form  two  side  aisles  in 
connection  with  the  nave ;  and  their  isolation  from  the 


40  ACOUSTICS. 

main  body  of  the  church  will  not  only  assist  strength, 
but  will  allow  a  variety  of  form  and  of  character  most 
suitable  to  the  church.  The  passage  in  front  of  the 
smallar  altars  will  be  a  passage  likewise  to  the  trans- 
verse seats  of  the  main  body  of  the  church ;  large  open- 
ings communicating  with  the  main  body  of  the  church 
are  avoided,  and  the  side  walls  of  the  nave  are  left  un- 
disturbed for  decoration,  and  facilitates  the  concentra- 
tion of  sound.  Ample  light,  also,  is  indisputably  gam- 
ed by  this  arrangement. 

The  front  of  such  an  inner  arrangement  will  admit  of 
two  towers  or  one,  and  an  exclusive  field  for  the  dis- 
play of  the  main  front  in  its  proper  characteristic  fea- 
ture noticed  on  all  the  basilica  forms. 

Large  door  and  window  openings  may  find  sufficient 
space,  also,  with  an  ample  portico,  etc.;  a  large  church, 
built  on  this  plan,  will  at  once  suggest  how  extensive 
a  variety  of  form  may  be  introduced ;  it  will  admit  even 
of  six  towers,  with  a  cupola  in  the  middle  of  the  tran- 
sept, and  an  inner  and  outer  decoration  may  be  ar- 
rived at,  worthy  of  the  house  of  God. 

I  will  now  proceed  with  the  form,  acoustics,  and  size, 
and  prove  that  the  basilica  form,  or  oblong  form,  is 
much  better  calculated  to  assist  sound  than  any  other. 

A  space  60  by  250,  arched  or  covered  with  a  hori- 
zontal ceiling,  forms  in  itself  a  tube  with  a  condensed 
volume  of  air,  having  the  tendency  to  restrain  the 
sound  from  spreading  sideways,  and  to  guide  it  in  a 
forward  direction  similar  to  a  pipe  or  tube,  which  we 
all  know  throws  the  sound  to  an  almost  incredible 


ACOUSTICS.  41 

distance.    Notwithstanding  this  space  is  of  large  size, 
the  influence,  nevertheless,  is  the  same. 

The  fact  is  proved  that  the  voice  in  large  spaces 
may  be  heard  150  feet  towards  the  front  of  the  speak- 
er, 80  feet  towards  each  side,  and  60  feet  to  the  rear  ; 
this  is,  however,  the  extreme  extent  under  very  favor- 
able circumstances.  This  simple  example  shows  how 
important  form  is  in  large  churches  to  assist  sound, 
and  requires  no  further  comment. 

Gothic  arches  have  been  considered  an>  obstruction 
to  sound,  not  only  owing  to  their  main  elevating  out- 
line, but  more  on  account  of  their  deeply  recessed 
forms,  which  naturally  create  points  for  reflection  in 
badly  ventilated  churches ;  but  large  columns  are  the 
most  objectionable  parts  of  the  church ;  they  not  only 
obstruct  sight,  but  give  successive  points  for  the  re- 
flection of  sound,  and  should  be  avoided  in  all  cases. 

In  the  upper  part  of  this  city  you  will  find  a  church 
in  oblong  form  with  a  pointed  roof,  where  you  cannot 
hear ;  this  case  seems  to  prove  a  contradiction,  but  by 
closer  examination  it  is  nothing  but  a  natural  conse- 
quence. The  roof  is  put  up  in  a  very  sharp  degree, 
and  rests  on  a  wall  not  very  high  from  the  floor  ;  in 
fact  this  construction  deprives  the  actual  aerial  space 
requisite  for  good  hearing  of  about  one-half  of  its  vol- 
ume. As  heat  is  introduced,  the  heated  air  rushes  up 
to  the  highest  point  under  the  roof  and  there  remains, 
and  the  sound,  in  consequence,  operates  in  this  very 
spot  so  congenial  to  its  nature,  and,  reflecting  from 
one  side  of  the  roof  to  the  other,  loses  its  effect  entirely 


42  ACOUSTICS. 

on  the  assembled  multitude.  A  sound-board  has  been 
introduced,  but  cannot  be  of  any  favorable  result.  In 
the  beginning  I  referred  to  art  being  necessary  to  con- 
struct  buildings  for  public  purposes,  and  equally  so  for 
large  aerial  spaces.  Art  teaches  us  to  create  proper 
proportions,  and  this  very  aesthetic al  feeling  requisite 
to  do  so,  should  at  once  put  a  stop  to  those  low  pro- 
portioned ceilings  which  always  form  an  eyesore  to  the 
cultivated  mind,  and  especially  in  a  church ;  good  pro- 
portioned halls  will  always  prove  to  be  correct  and  in 
harmony  with  the  aerial  space  necessary  for  good  ven- 
tilation and  hearing ;  it  is  strange,  but  nevertheless 
true,  that  nature  and  science  go  hand  in  hand,  and  to 
succeed  it  is  absolutely  necessary  to  be  perfectly  at 
home  with  the  study  of  the  different  branches  of  sci- 
ence and  art. 

Church  architecture  of  the  middle  ages  proves  the 
spirit  of  that  age ;  religious  feeling  was  at  its  highest 
point,  and  was  sure  to  produce  the  most  sublime 
effects  human  nature  possessed,  but  nevertheless  it 
has  proved  to  be  one-sided,  after  all ;  it  carried  the 
human  souls  too  far  above  the  sphere  of  our  worldly 
life,  and  could  not  exist  for  any  length  of  time.  We  see 
what  art  was  capable  of  performing,  stimulated  by 
religious  feelings ;  but  that  time  has  passed  away,  and 
we  are  now  in  a  sphere  of  worldly  materialism.  The 
present  churches  prove  it ;  a  change  is  desirable,  and 
would  it  not  be  best,  at  least,  to  profit  by  the  golden 
grains  left  to  us,  and  add  practical  alterations  for  good 
sight  and  hearing  in  our  future  construction  of  churches 


ACOUSTICS.  43 

and  other  buildings,  so  that  the  house  of  worship,  as 
well  as  the  lecture-room,  will  become  more  attractive, 
and  assist  the  advance  of  human  progress  ?  Let  us  do 
away  with  heavy  stone  columns,  introduce  iron  col- 
umns as  sight  requires  the  change,  and  confine  our- 
selves to  those  forms  best  adapted  to  the  purpose,  and 
churches  and  other  buildings  will  present  an  attraction 
of  a  powerful  nature  to  lead  the  aspiring  individual 
and  penitent  sinner  to  his  home.  Very  large  supports 
or  columns  in  our  churches  only  obstruct  the  sight 
and  sound,  in  fact,  they  are  merely  introduced  for  an 
imposing  effect,  nothing  else,  as  the  ceilings  of  almost 
all  our  churches  are  constructed  of  wood  and  plas- 
tered. Iron  columns  will  answer  the  same  purpose  as 
to  strength,  and  are  more  in  keeping  with  the  con- 
struction. In  some  churches  in  this  city  where  stone 
piers  are  introduced,  the  amount  of  their  cost  would 
have  actually  been  sufficient  to  construct  the  entire 
building  fire-proof,  with  iron  and  bricks,  and  the 
building  would  have  exhibited  a  greater  aerial  space 
and  a  clearer  sight  in  the  interior.  Iron  construction 
will  eventually  step  in;  although  many  will  protest 
against  it,  it  is  the  only  construction  for  our  present 
wants,  especially  where  galleries  to  any  extent  are 
required. 

Iron  construction  in  the  interior  of  churches  and 
public  buildings  is  not  new ;  in  secular  buildings  we  use 
it  daily,  but  in  the  interior  the  iron  constructions  are 
very  seldom  modelled  to  answer  a  constructive  part  of 
decoration,  in  which  there  is  a  large  field  for  improve- 


44  ACOUSTICS. 

raent.  In  Prussia  iron  construction  is  already  intro- 
duced in  churches  and  other  buildings  with  artistic 
skill ;  and  it  certainly  should  not  be  neglected  in  this 
country. 

Now  we  will  examme  the  wants  of  Protestant 
churches  of  smaller  and  larger  size.  It  will  not  be 
without  interest  to  add  a  few  remarks  relative  to  the 
progress  of  Protestant  churches  up  to  the  present 
time,  to  prove  how  large  a  field  there  is  still  open  for 
the  future  in  this  particular  branch. 

"  In  Prussia  and  in  England  this  interesting  subject 
has  had  its  due  weight,  and  progress  has  been  made  to 
a  certain  extent.  In  Europe,  for  the  past  2|  centuries, 
the  Protestants  have  been  content  to  use  the  Catholic 
churches  that  fell  to  their  inheritance,  and  in  the  erec- 
tion of  new  churches  they  have  followed  the  plan  of  the 
Catholic  churches,  with  the  introduction  of  plain  galle- 
ries, and  without  any  metaphorical  decorations." 
"  In  England,  in  Protestant  churches,  in  their  inner 
arrangement,  the  vigorous  zeal  to  conform  to  the  pres- 
ent demands  was  first  visible."  "  In  Germany  (Prus- 
sia) "  Schinkel,"  the  great  architect,  was  the  first  who 
appeared  as  a  reformer  in  this  direction,  and  a  num- 
ber of  his  plans  show  a  distinct  separation  from  the 
main  body  of  the  church  and  USie  chancel,  inclosing  the 
altar  service  and  a  distinct  Baptistery.  Somewhat  la- 
ter this  direction  was  followed  up,  and  two  scholars  of 
"  Schinkel,"  two  very  eminent  architects  in  the  Prus- 
sian service,  were  ordered  to  visit  England  and  other 
countries,  to  inform  themselves  of  every  new  arrange- 


ACOUSTICS.  45 

ment  that  might  have  been  made,  and  after  their  re- 
turn they  exhibited  to  the  Prussian  Government  a 
number  of  plans  of  churches  for  villages  and  for  cities 
of  smaller  dimensions  ;  these  plans  were  all  adopted  by 
the  Prussian  Government,  and  ordered  to  be  published 
as  a  standard  to  be  followed  in  all  new  constructions 
of  similar  demands.  The  plans  of  the  smallest 
churches  published,  in  almost  all  cases  represent  the 
oblong  form  ;  the  body  of  the  church  is  undivided,  gal- 
leries are  mostly  left  out,  the  ceiling  always  construct- 
ed in  wood,  and  the  construction  itself  in  every  plan  is 
taken  up  as  a  motive  for  decoration  and  inner  life." 
"  The  chancel  inclosing  the  altar  service,  is  mostly 
closed  in  an  apsis  form,  very  seldom  in  a  straight  line  ; 
the  pulpit  is  placed  sideways  before  the  altar,  where 
the  chancel  comes  in  contact  with  the  body  of  the 
church,  and  on  the  side  of  the  altar  generally  termed 
by  Catholics  the  evangelical  side.  The  font  is  placed 
in  the  longitudinal  axis  of  the  building,  below  the  lev- 
el of  the  steps  leading  to  the  altar.  The  exterior  is 
very  plain;  burnt  brick  is  the  prominent  material. 
To  harmonize  with  the  material,  and  to  give  life  and 
character,  the  principal  forms  of  the  middle  ages  are 
predominant ;  a  more  picturesque  than  severe  style  of 
characteristic,  however,  is  introduced."  This  very 
picturesque  stamp  would  be  very  desirable  for  our  vil- 
lage churches,  and  for  smaller  cities,  where  the  monot- 
ony of  frame  buildings  is  too  frequently  visible.  It  is 
true,  the  English  in  their  churches  have  often  made 
the  attempt  to  create  picturesque  forms,  but  each  na- 
tion seems  to  have  its  own  peculiar  taste. 


46  ACOUSTICS. 

"  That  the  small  Protestant  churches  in  their  whole 
form  cannot  deviate  from  the  Catholic  church  or 
chapel  is  a  natural  consequence ;  only  larger  dimen- 
sions will  cause  the  historical  forms  of  the  Catholic 
church  building  to  come  in  conflict  with  the  material, 
and  partly,  in  a  certain  sense,  with  the  ideal  demands 
of  the  Protestant  churches,  and  consequently  in  laiger 
Protestant  churches  a  peculiar  varying  formation  be- 
comes a  necessity,  and  a  discriminating  character  is 
only  then  possible,  and  so  the  characteristic  of  large 
size  churches  will  depend  on  the  form,  the  manner, 
and  the  place  allotted  to  the  pulpit  and  font,  and  in  the 
arrangement  of  galleries  ;  besides  those  positive 
changes,  there  are  some  more  negative  variations  of 
rather  smaller  interest." 

"  The  plans  published  by  the  Prussian  Government 
for  churches  of  middle  size  are  of  the  oblong  basilica 
and  central  square  polygon  form,  somewhat  like  the 
Grecian  cross.  Churches  of  those  named  forms  are 
best  calculated  for  Protestant  churches ;  the  voice  of 
the  clergyman  is  better  heard  in  them  ;  they  admit  of 
deeper  galleries,  and  seat  more  people.'* 

"  The  Catholics,  however,  at  this  newer  time  often 
introduce  galleries,  and  nobody  can  deny  that  they  are 
very  useful ;  the  opinion  of  the  past  eighteen  centuries, 
that  churches  shall  not  be  constructed  for  profitable 
theories,  is  laid  aside  and  somewhat  antiquated.  Very 
large  Protestant  churches  will  have  to  fall  back  upon 
the  plan  of  the  oblong  form  with  galleries,  with  a 
similar  arrangement  first  described  for  Catholic 


ACOUSTICS.  47 

churches."  The  extent  of  hearing  has  its  limit,  and  if 
we  require  churches  of  immense  capacity  we  have  to 
fall  back  on  forms  which  are  calculated  to  assist  sound, 
with  good  ventilation.  The  basilica  form  may  be 
extended  to  300  feet  in  length;  but  concentrated  forms," 
such  as  the  square,  will  never  answer  the  purpose  for 
good  hearing.  A  very  striking  example  is  one  of  the 
churces  in  the  upper  part  of  this  city,  not  very  large, 
but  nearly  square ;  the  sight  is  good,  but  the  sound 
quite  unintelligible  in  many  parts  of  the  building.  It 
is  not  alone  that  the  inside  proves  how  little  the  form 
was  understood,  but  more  striking  by  the  outside. 
The  form  of  the  church  represents  a  barn  with  an  im- 
mense roof.  The  two  towers  in  front  are  a  mixture  of 
Gothic  and  Romanesque,  the  Gothic  elevated  spirit 
predominating  strongly  in  contrast  with  the  body  of  tho 
church,  rarely  to  be  seen.  In  this  church  we  find  two 
elements  ;  the  one  has  special  claim  to  materialism, 
and  the  other  to  an  aspiring  sphere,  a  most  inhar- 
monious whole,  and  unfortunately  the  aspiring  spirit  is 
on  the  outside. 

To  characterize  the  interior  of  the  church  in  front 
was  an  impossibility ;  if  it  had  been  insisted  on,  the 
barn  form  would  have  been  still  more  striking,  and 
therefore  the  architect  felt  himself  bound  to  place  two 
elevating  towers  in  front  to  hide  the  mistake,  and  es- 
pecially in  such  a  prominent  situation.  True  harmony 
can  only  be  produced,  if  the  inner  life  is  strictly  follow- 
ed in  the  outer  forms ;  in  this  case  the  galleries  are 
secondary,  and  form  no  principal  divisions  in  the  inte- 


48  ACOUSTICS. 

rior,  consequently  the  towers  are  inorganically  con- 
nected with  the  body  of  the  church.  Square  forms  of 
large  size,  or  those  nearly  square,  require  an  entirely 
different  arrangement,  and  should  never  be  used  for 
very  large  churches  ;  aside  from  acoustics,  larger  sizes 
of  timbers  are  necessary,  and  the  decoration  has  to 
be  rather  pretentious,  or  the  building  will  look  empty, 
and  will  more  or  less  leave  an  impression  of  monotony. 
"  In  very  large  Protestant  churches,  where  galleries 
have  to  be  introduced,  and  on  a  large  scale,  the  oblong 
form,  with  nave  and  two  side  aisles,  becomes  a  neces- 
sity ;  in  such  cases  it  is  desirable  to  add  a  transept  of 
sufficient  projection  to  allow  more  concentration.  With 
entrances  or  outlets  on  each  side,  with  enclosed  pas- 
sages and  stairs  leading  to  galleries  extending  the  main 
body  of  the  church  from  front  to  rear  beyond  the 
transept,  with  one  division  beyond  the  transept  ad- 
joining the  chancel,  and  allowing  the  centre  division  of 
the  transept  to  be  double  in  size  in  comparison  with 
the  other  divisions,  and  three  of  the  smaller  divisions 
for  the  body  of  the  church  in  front,  a  concentration  is 
gained  with  two  side  aisles  and  nave  which  will  give  a 
grand  aerial  space,  and  admit  of  a  large  number  of 
seats  around  the  pulpit.  The  pulpit  may  be  placed  on 
the  side  of  the  column  at  the  intersection  of  the  nave 
and  transepts,  and  a  richly  decorated  chancel ;  the 
whole  will  produce  an  opulent  and  rather  an  unusual 
arrangement,  only  noticed  in  large  cathedrals.  This 
will  be  the  form  for  large  Protestant  churches,  and  no 
other ;  but  we  must  not  forget  that  there  is  a  certain 


ACOUSTICS.  49 

extent  in  size  which  we  cannot  overstep."  Churches 
with  transepts  in  connection  with  side  aisles,  even 
with  two  or  more  aisles ;  polygons,  no  matter  of 
what  form  of  plan,  will  eventually  assist  much  in  the 
formation  of  public  monuments  to  comply  with  all  our 
wants ;  and  the  Catholics  will,  if  they  do  not  insist 
upon  retaining  large  surfaces  of  walls  for  other  pur- 
poses, use  similar  forms,  as  they  have  done  already  in 
some  cases,  and  fall  back  upon  the  original  form  of  the 
divided  oblong. 

"  It  cannot  be  doubted  that  a  centralization  of  form 
appears  to  have  advantages  ;  but,  after  all,  it  will  not 
compare  with  the  oblong  form,  which  concentrate's  the 
view  to  one  spot  only,  viz. :  the  altar,  the  most  promi- 
nent point ;  and  it  suggests  itself  that  central  forms  for 
churches  have  not  been  based  upon  the  requirements 
of  the  liturgy ;  altogether,  to  produce  a  majestic  and 
imposing  effect,  which  conforms  to  the  early  Christian 
works  of  this  class,  it  is  not  to  be  wondered  that  the 
noble  construction  of  a  cupola,  in  its  inner  and  outer 
grandeur,  and  with  the  charming  effect  of  the  upper 
light  in  contrast  with  the  more  plain  form  of  the  basil- 
ica, should  have  been  favored.  The  oblong  form, 
with  only  one  division,  will  centralize  to  a  greater 
extent  than  more ;  but  the  construction  of  monumen- 
tal buildings  in  this  form  becomes  expensive  owing  to 
its  great  height  in  proper  proportion,  whereas  in  divi- 
ding the  width  of  the  building  into  nave  and  two  side 
aisles,  the  height  is  much  diminished  in  proportion  to 
its  width.  The  idea  of  building  churches  and  even 


50  ACOUSTICS. 

theatres  to  contain  from  four  to  five  thousand  seats  with 
a  clear  sight  and  with  perfect  acoustics,  is  a  mistake, 
and  can  only  be  entertained  by  architects  who  are 
strangers  to  science.  Three  thousand  five  hundred 
seats  placed  in  one  space,  with  comfort,  forms  the 
culminating  point  of  hearing,  and  any  attempt  to 
extend  the  number  of  seats  further  rests  on  an  assump- 
tion of  knowledge  which  does  not  exist.  All  the  reports 
spread  abroad  that  there  are  churches  and  theatres 
containing  five  thousand  seats,  is  an  error;  and  if  there 
should  be  a  building  of  such  a  class,  you  may  be  sure 
that  you  cannot  hear  in  all  parts  of  it.  Now  I  will 
present  the  reader  with  facts  relating  to  the  minimum 
extent  of  aerial  cubic  feet  requisite  for  good  hear- 
ing, facts  which  I  gained  by  many  years  observations 
in  examining  buildings  where  the  acoustics  are  con- 
sidered good,  and  public  buildings,  theatres,  and 
churches  of  the  largest  size  which  came  under  my 
direct  care.  Churches,  halls,  lecture-rooms,  etc.,  con- 
taining not  more  than  one  thousand  seats,  should  not 
have  less  than  150  cubic  feet  aerial  measure  for  each 
person. 

Churches  .containing  2,000  persons,  not  less  than 
from  250  to  300  cubic  feet  aerial  for  each  person,  and 
an  increase  to  from  300  to  500  in  proportion  to  the 
number  of  persons ;  500  cubic  feet  aerial  will  answer  for 
3,500  persons,  even  550  cubic  feet  aerial  will  not  be 
out  of  proportion  with  a  calculation  of  about  6  square 
feet  to  one  seat;  if  more,  the  aerial  space  will  consume 
too  much  sound  and  will  lose  its  force.  Five  hundred 


ACOUSTICS.  51 

cubic  feet  aerial  space  will  keep  an  audience  pretty 
comfortable  for  an  hour,  as  to  breathing;  but  never- 
theless, the  sound  begins  to  rise  after  this  space  of 
time,  and  appears  distinct  for  a  short  period  only, 
emanating  from  the  pulpit  about  10  feet  above  the 
floor,  but  loses  its  strength  gradually,  and  then  the 
lower  strata  of  air  become  specifically  heavier  and 
the  sound  less  audible,  and  persons  occupying  the 
principal  seats  in  the  nave  naturally  suffer  the  most. 
A  thorough  ventilation  with  proper  form  to  assist 
sound,  willl  be  absolutely  necessary  to  remedy  the 
difficulty.  All  the  above  aerial  proportions  will,  if 
properly  applied,  form  another  link  of  the  consistency 
of  nature,  which  never  deceives. 

It  may  be  readily  seen  that  a  proper  ventilation, 
consisting  of  a  proportionate  supply  of  fresh  air,  and  a 
proportionate  outlet  of  bad  air,  is  as  necessary  as  the 
sound  itself,  for  sound,  to  be  distinctly  heard ;  and 
hence  it  follows  that  churches  and  theatres  with  abun- 
dance of  aerial  measure,  are  often  better  adapted  for 
hearing  than  buildings  of  a  smaller  size,  where  the  air 
is  impure  and  has  less  opportunity  to  diffuse  itself,  and 
the  necessity  of  ventilating  smaller  public  buildings  is 
in  one  sense  of  more  importance  than  in  larger  build- 
ings ;  this  depends,  however,  solely  upon  the  time  of 
actual  use.  A  church,  or  a  theatre,  or  a  lecture-room 
occupied  for  one  hour's  time,  will  prove  better  for  hear- 
ing than  for  two  hours,  and  so  on  ;  and  halls  occupied 
the  whole  day,  like  the  Senate  Chamber  and  Hall  of 
Representatives  in  the  Capitol  at  Washington,  without 


52  ACOUSTICS. 

the  proper  aerial  measurement  and  with  insufficient 
ventilation,  prove  failures. 

In  all  cases  where  a  public  hall  is  occupied  for  half 
a  day  or  more,  an  increase  of  aerial  measure  for  each 
person  should  be  adopted,  as  the  present  mode  of 
ventilation  cannot  be  relied  on. 

The  form  of  our  churches  which  we  see  daily  in  this 
city  and  in  the  country,  with  immense  roofs  resting  on 
stone  walls  only  10  feet  high,  and  sometimes  divided 
in  the  interior  into  nave  and  side  aisles,  with  a 
high  tower  on  one  of  the  corners,  is  an  attempt  to  ele- 
vate the  building  to  a  characteristic  which  it  does  not 
deserve,  and  may  be  termed  an  excessive  economical 
measure,  regardless  of  the  inner  life,  placing  the  eleva- 
ting spirit  on  the  outside  only.  And  the  church  com- 
mittee who  protests  against  such  unnatural  forma 
should  receive  thanks  for  unerring  zeal,  if  only  rest- 
ing on  an  intuitive  feeling  of  propriety. 

"Wooden  ceilings  and  open  roofs  are  often  very  desi- 
rable and  have  many  advantages,  but  they  should 
never  be  used  except  for  smaller  churches  ;  they  will, 
if  properly  arranged,  allow  a  very  desirable  decoration 
for  the  interior.  The  open  roof  allows  more  height 
for  the  interior  of  a  church,  and  may  be  placed  on 
much  lighter  walls,  by  which  expense  is  saved ;  but 
in  many  cases  the  roof  forms  the  most  prominent  part 
of  the  church,  and  such  extremes  lead  to  caricatures 
of  a  most  striking  nature. 

There  is  no  cause  for  fear  that  the  open  timber  roof 
diminishes  the  church -like  appearance  of  the  interior, 


ACOUSTICS.  53 

If  the  constructive  timbers  are  only  properly  arranged, 
and  treated  with  a  fine  sesthetical  feeling,  with  suitable 
mouldings,  etc.,  and  harmonizing  colors,  a  most  beau- 
tiful and  impressive  effect  is  gained ;  but  in  large 
monumental  works  the  arch  has  and  always  will  be 
the  most  effective  form  for  an  impressive  and  elevating 
characteristic. 

Hitherto  it  has  always  been  noticed  that  the  ceilings 
of  churches  and  of  other  public  building  have  had  an 
important  influence  upon  acoustics  ;  and  wooden  ceil- 
ings and  groined  arches  have  proved  to  be  better 
suited  than  the  semicircular  arches,  etc.;  this  is  very 
true,  and  could  not  have  been  otherwise  ;  but  groined 
arches,  and  even  wooden  ceilings,  as  we  often  see 
them,  have  in  many  cases  created  bad  effects.  In  one 
church  in  Fort  Wayne,  State  of  Indiana,  constructed 
with  a  wooden  ceiling,  it  was  impossible  to  hear,  and 
the  confused  echoes  were  actually  sent  forth  from  this 
wooden  ceiling.  I  could  mention  many  examples  of 
the  same  effect,  and  why  ?  From  the  want  of  ventila- 
tion, the  force  of  the  sound  was  concentrated  to  the 
ceiling  alone,  and  through  its  force  those  very  phe- 
nomena were  visible  ;  and  so  it  will  be  with  any  arch, 
and  especially  with  a  cupola,  that  rises  above  the  level 
of  the  church  ceiling.  The  heat  will  rise  to  those 
parts  and  invite  the  sound  to  follow,  and  it  does  follow 
with  force,  and  its  general  diffusion  throughout  the 
church  is  lost.  Now,  is  it  not  easy  to  comprehend 
that  if  the  air  in  a  church  or  any  other  public  build- 
ing is  heated  equally,  and  the  ventilation  good,  the 


51  ACOUSTICS. 

diffusion  of  sound  will  be  more  equal  throughout  every 
part,  and  that  the  reflection  of  sound,  caused  by  pro- 
jections and  recesses  will  be  less,  especially  when  the 
points  of  contact  are  at  a  considerable  distance  ?  At 
this  very  moment  I  have  received  from  Berlin  an 
architectural  work  in  which  Dr.  Dove,  a  Professor  of 
Science  in  Berlin,  and  a  very  eminent  man,  gives  his 
views  relative  to  the  rules  of  acoustics,  to  be  observed 
in  the  erection  of  a  new  dome  or  cupola  in  the  city  of 
Berlin.  His  treatise  is  interesting,  and  I  think  a 
translation  into  the  English  language  will  not  be  out 
of  place,  as  I  intended  to  proceed  with  the  same  iden- 
tical subject. 

"  The  problem  which  has  been  stipulated  upon 
practical  acoustics  can  be  named  as  the  very  reverse 
to  that  which  optics  have  to  solve.  All  the  rays 
which  emanate  from  an  illuminated  body  shall  be  con- 
centrated into  a  point  to  reproduce  the  same  picture, 
which  on  that  account  could  only  be  discernible  at  a 
certain  point,  whereas  the  sound  rays  shall  be  equally 
distributed,  so  that  no  one  individual,  placed  at  a  cer- 
tain point,  shall  alone  hear  the  orator,  but  large  num- 
bers placed  at  different  points  shall  hear  him  equally 
distinctly.  The  ages  of  antiquity  have  done  nothing 
to  assist  practical  optics,  notwithstanding  they  have 
done  more  in  single  cases  than  the  present  age  for 
practical  acoustics.  The  point  of  view  which  has 
guided  the  architects  of  the  past  ages  in  their  con- 
struction of  temples  and  theatres  appears  to  be 
entirely  of  an  empiric  nature,  and  in  fact  a  greater 


ACOUSTICS.  55 

experience  was  at  their  disposal  as  long  as  communi- 
cation was  predominating,  based  upon  the  living  word 
in  its  place  ;  writing  was  very  little  known,  and  print 
altogether  unknown.  Besides,  the  recitative  may 
often  have  been  substituted  in  the  place  of  the  com- 
mon speech,  for  report  says  that  an  orator  of  the  olden 
time  required  a  musician  of  the  flute  to  .direct  the 
tone  of  his  speech.  It  may  be  taken  for  granted  that 
a  thorough  theory  relating  to  the  propagation  of 
sound  rays  was  entirely  out  of  the  question,  and 
particularly  at  a  time  when  experiments  were  un- 
known. It  is  only  in  this  century  that  the  laws  in 
which  sound  in  its  commotion  and  in  its  propaga- 
ting oscillatory  motions  have  been  settled,  and  hence 
science  is  too  young  to  fill  the  chasm  left  by  Antiquity 
with  precise  theoretical  observations.  Tones  called 
forth,  directly  perceptible  at  a  certain  point,  can  be- 
come indistinct  when  the  sound  waves,  emanating 
directly  from  the  sounding  body  agitated  at  other 
points,  come  in  contact  with  each  other,  or  by  their 
self-created  reflections  from  various  objects.  The 
surrounding  stillness  requisite  to  distinct  hearing  will 
obviate  the  first  difficulty  ;  in  the  second  case,  which 
demands  here  especial  attention,  there  are  several 
species  to  be  discriminated.  Since  the  propagating 
sound  waves  are  actually  produced  by  their  succes- 
sively following  condensations  and  attenuations  in 
equal  distances,  and  by  the  intersection  of  the  sound 
rays  at  certain  points  when  their  paths,  crossing  in 
different  lengths,  happen  to  meet  with  the  condensa- 


56  ACOUSTICS. 

tion  produced  in  one  case,  and  with  the  attenuation  in 
the  other.  In  this  case  the  air  will  not  be  condensed 
or  dilated ;  stillness  is  produced  by  the  converging 
sounds  of  the  same  height,  however  oscillatory  the 
motion  may  be,  which  increase  or  decrease  the  force 
of  the  tones,  if  the  respective  contrast  of  the  conden- 
sation differs  in  each  case  whenever  the  rays  cross 
each  other. 

We  will  designate  this  problem  with  the  name  inter- 
ference. But  the  deeper  the  tone  the  greater  the  differ- 
ence between  the  condensation  and  attenuation  ;  for 
instance,  by  the  deepest  sound  of  our  organs  16  feet, 
and  by  the  highest  sound  of  the  human  voice  |  inch, 
and  in  consequence  some  sounds  at  a  certain  height 
may  be  destroyed  and  others  become  perfectly  clear. 

The  enclosure  of  great  spaces  for  acoustic  purposes, 
rendered  necessary  by  our  climate,  naturally  increases 
the  stipulated  reflections  in  a  manner  unknown  in  the 
ancient  theatres. 

By  the  medium  temperature  of  Berlin  (7°  B)  sound 
passes  through  a  distance  of  1,050  Paris  feet  in  a 
second,  at  the  freezing  point  333  metres.  If  a  reflect- 
ing wall  is  at  a  distance  of  525  feet  from  the  point 
where  the  sound  emanates,  and  it  strikes  directly 
upon  the  surface,  it  will  return  in  a  second  to  the 
point  of  emanation.  The  nearer  the  wall  the  quicker 
the  reflection  follows  the  sound,  as  it  is  impossible 
to  distinguish  more  than  ten  tones  in  a  second  if  the 
distance  is  about  53  feet.  The  smoother  the  reflect- 
ing surface,  the  more  the  reflecting  sound  increases  to 


ACOUSTICS.  57 

a  certain  extent.  But  for  the  long  sound  waves  the 
surface  which  is  considered  coarse  for  light  is  already 
to  be  viewed  mirror-like.  To  diminish  and  control 
the  condition  and  effect  of  the  reflecting  sound  rays 
can  be  correspondingly  acted  upon  in  two  ways ;  first, 
by  changing  the  surface  of  the  reflecting  walls,  and 
secondly,  through  the  form  applied  to  them. 

The  result  in  lessening  the  reflection  will  be  that 
the  irritated  tones  will  operate  the  same  as  those  pro- 
duced in  an  enclosed  space.  It  is  evident  that  the 
effect  in  an  enclosed  space  which  produces  tones 
depends  much  upon  the  points  where  they  are  pro- 
duced or  created.  In  a  circular  building  there  are 
naturally  many  points  which  in  relation  to  the  reflec- 
tion of  sound  compare  equally,  as  all  points  corre- 
sponding to  the  circumference  of  a  concentric  circle 
comply  with  this  condition.  In  the  centre  the  echo  is 
stronger  because  the  reflecting  rays  all  of  one  distance 
must  accumulate  in  their  effect.  A  most  astounding 
example  is  the  arch  of  the  cupola  of  the  old  Museum 
of  Berlin.  And  likewise  is  the  centre  the  point  from 
which  the  words  of  the  speaker  are  most  homogene- 
ously heard  if  the  seats  of  the  audience  are  arranged 
concentric,  similar  to  those  in  an  amphitheatre.  The 
theatre  in  the  villa  of  Hadrian  at  Tivoli,  the  circus  of 
Murviodore,  the  amphitheatre  at  Nismes,  prove  this, 
as  all  the  words  uttered  in  the  arena  are  distinctly 
heard  at  all  points.  The  voices  of  singers,  however, 
become  entirely  inverse  if  seated  on  concentrated 
seats ;  the  voice  unites  harmoniously  in  all  parts.  For 


58  ACOUSTICS. 

church  music,  however  there  is  very  seldom  such  an 
arrangement.  An  astounding  effec^  I  had  an  oppor- 
tunity of  noticing  in  St.  Paul's  Cathedral  in  London. 
Amphitheatre-like  seats  were  erected  for  three  thou- 
sand orphans,  directly  under  the  dome,  and  when 
the  singing  commenced  the  effect  was  sublime. 
The  more  remote  we  are  from  the  centre  point 
the  less  will  be  the  equal  perceptibility  on  all  points 
of  the  circle ;  for,  if  the  sound  rays  are  noticed 
which  spread  perpendicularly  on  the  radius  of  the 
curve,  it  is  plain  to  see  from  a  simple  plan  that  on 
certain  points  many  reflecting  rays  cross  each  other, 
and  in  other  places  only  a  small  number,  and  it  follows 
directly  that  the  perceptibility  on  various  points  must 
be  very  different.  This  conforms  also  to  the  hori- 
zontal section  (a  well-known  example  of  which  is  the 
whispering  gallery  in  St.  Paul's  Cathedral,  London), 
as  well  as  to  the  perpendicular  section  of  cupola 
arches.  It  is  the  case  here,  as  in  the  Palace  chapel  in 
Berlin  ;  by  placing  singers  on  a  continued  gallery 
under  the  cupola-arched  ceiling  to  perform  church 
music,  the  music  is  distinctly  heard  by  every  one, 
whereas  the  voice  of  a  clergyman  placed  in  a  position 
not  high  above  the  altar  will  produce  reflection  of 
sound  unintelligible  at  many  points. 

The  difficulty  of  the  problem  to  erect  churches 
with  good  acoustic  qualities  depends  in  general  on 
very  different  conditions,  to  comply  with  all  of  which 
simultaneously  would  be  impossible. 

The  spoken  words  do  not  require  an  identical  con- 


ACOUSTICS.  59 

stniction  of  the  interior  for  good  hearing  with  that 
requisite  for  a  musical  piece,  if  they  were  even  ema- 
nating from,  one  point ;  and  this  fact  prevents  con- 
versational pieces  being  carried  out  in  opera-houses 
with  any  success  ;  and  from  this  very  cause  it  is  im- 
possible for  the  voice  of  a  clergyman  to  fill  the  space 
of  a  dome,  originally  intended  for  the  execution  of 
grand  musical  compositions  to  accompany  the  mass. 
In  public  speaking  the  strength  of  sound  is  much  im- 
paired by  the  walls  producing  reflections,  and  hence 
less  distinctness;  whereas  the  walls  of  the  concert-room 
are  often  lined  with  wood,  to  give  a  higher  and  more 
marked  tone.  And  from  this  very  cause,  too,  pianos 
which  are  for  sale  are  placed  on  elevated  reverbera- 
ting platforms  or  floors,  as  curtains,  tapestry,  carpets, 
richly  cushioned  chairs,  will  materially  weaken  the  re- 
sonance. In  St.  Paul's  Church,  in  Boston,  it  is  said 
that  the  clergyman  is  only  heard  at  Christmas  time, 
the  church  being  then  decorated  with  drapery.  Can- 
on Mills  proved  perfect  in  regard  to  acoustics  for  the 
service  of  the  meeting  of  the  Free  Church  in  Scotland, 
as  long  as  the  walls  were  left  unfinished,  whereas  oth- 
er buildings  with  finished  walls  showed  most  impor- 
tant acoustic  defects.  The  cause  of  these  different  ef- 
fects of  the  walls  on  speech  and  sound  is  this,  they  acid 
force  to  countless  consonants,  and  a  noise  is  produced 
which  does  not  appear  when  clear  tones  are  constant- 
ly repeated.  A  covered  space  in  form  of  a  prolonged 
square  or  oblong,  has  proved  to  be  best  for  acoustic 
purposes,  provided  the  tones  originate  oa  one  of  the 


60  ACOUSTICS. 

smaller  sides,  and  that  the  place  of  the  originating 
tones  be  higher  than  the  space  filled  with  hearers,  so 
that  those  seated  in  front  may  not  intercept  the  tones 
from  those  seated  behind.  In  this  case  the  forward 
moving  sound  rays  are  especially  directed  to  the  space 
occupied  by  the  audience.  The  Berlin  Singing  Acade- 
my proves  itself  in  this  respect  perfect.  Should  it  be 
desired  to  give  more  distinctness  to  the  words,  a  half 
cylinder  might  be  added  to  the  extended  square,  and 
with  such  a  curve  that  the  reflecting  sound  rays  from 
its  own  walls  follow  parallel  with  the  more  extended 
sides  of  the  square.  With  a  parabolic  curve,  the  speak- 
er should  be  situated  at  the  focus  of  the  parabolic 
transverse  section  ;  with  a  spherical,  his  standpoint 
should  be  at  the  distance  of  J  of  the  radius  from  the 
middle  of  the  surrounding  walls.  Should  the  building 
be  arranged  for  both  hearing  a  speech  and  a  musi- 
cal piece,  a  different  point  would  have  to  be  selected 
for  each  ;  for  the  orator,  the  end  of  the  building,  with 
the  cylindrical  curve,  and  for  music  (organ  and  church 
music)  the  shorter  and  straight  side  of  the  extended 
square.  These  main  conditions  have  been  generally 
introduced  into  Christian  churches,  and  the  basilica  of 
the  ancients  has  been  their  model. 

The  main  ground  form  of  the  basilica  forensis  was 
an  oblong  or  extended  square,  with  a  semicircular 
apsis,  and  an  elevated  tribune  adjoining  for  counsel- 
lors, with  a  small  vestibule  enclosing  the  whole  width 
of  the  building  on  the  opposite  side  of  the  niche. 
The  semicircular  extension  is  about  one-half  of  the 


ACOUSTICS.  61 

middle  part  of  the  whole  building,  which  proved  good, 
practically,  and  authenticated,  by  the  speaking-tube, 
that  the  voice  of  the  speaker  is  much  strengthened, 
when,  from  his  stand-point,  the  sound  rays  are  more 
restrained  from  spreading  sideways.  The  proportion 
of  the  transverse  section  of  the  semicircular  apsis  to 
the  width  of  the  building  had  the  tendency,  in  the 
construction  of  churches,  to  cause  the  division  of  the 
space  by  columns,  into  a  nave,  with  two  side  aisles. 
At  the  place  of  the  Chancellor's  seat,  in  the  Basilica 
Dominica,  the  Bishop's  cathedra,  semicircular  with 
his  Preebytery,  was  substituted.  But  in  front  of  the 
nave  and  side  aisles  a  transverse  space  of  larger  width 
was  introduced,  and,  later,  the  transept,  which  estab- 
lished the  cross  form  of  churches,  with  the  altar  in  the 
middle.  Then,  the  Bishop's  chair  was  removed  farther 
to  the  rear,  with  an  enclosure  to  confine  the  lower  grade 
of  divines,  whereas  the  nave  and  side  aisles  were  al- 
lotted to  the  people.  On  the  side  of  the  three  main 
divisions,  the  altar-house,  characteristically  marked  by 
the  direct  adjoining  quadratic  space,  and  the  transept, 
with  a  triple  width  of  the  chancel,  and  the  main  body 
of  the  house,  with  the  nave ;  the  first  two  were  higher 
than  the  third.  Below  them,  often  a  "  Krypta  "  was 
found,  and  sometimes,  a  passing  street.  The  eleva- 
tion of  the  chancel  is  one  of  the  most  important  ar- 
rangements for  acoustics,  and  this  arrangement  has 
been  essentially  retained  also  in  Gothic  buildings,  only 
differing  in  the  continued  curve  being  changed  to  the 
polygonal.  If  the  transept  is  further  removed  from 


62  ACOUSTICS. 

the  chancel,  then  the  ground  form  changes  to  that  of  a 
perfect  cross.  By  adding  to  the  cylindrical  extension 
the  whole  diagonal  section  of  all  the  divisions  of  the 
church,  then  the  acoustic  requirements  are  partially 
assisted  ;  then,  also,  a  passage  round  the  chancel  may 
be  arranged  so  that  the  chancel  may  retain  its  smaller 
proportions.  The  grand  effect  of  church  music  in 
large  spaces  is,  undoubtedly,  enhanced  by  the  right 
angle  form ;  the  broken  lines  of  the  arches,  the  large 
openings  left  on  the  upper  parts  in  the  side  walls  of 
the  nave,  and  sound  openings  in  the  ceiling,  are  of  the 
greatest  importance,  especially  in  very  large  churches, 
where  a  possibly  created  echo  may  be  removed  by  be- 
ing intercepted.  On  the  whole,  in  reference  to  sym- 
metrical arrangement  upon  the  longitudinal  axis,  no 
intimation  is  in  existence  of  a  demand  in  such  a 
building  to  gain  a  third  point  acoustically,  in  compari- 
son with  the  end  point  of  the  longitudinal  axis. 
Where,  then,  shall  the  pulpit  be,  as  the  sermon  forms 
the  centre  of  gravity  of  the  Protestant  worship  ?  It  is 
architecturally  so  disturbing  to  the  eye,  that,  in  the 
Basilica  in  Munich,  when  not  in  use,  it  is  always 
moved  aside. 

Here  are  then  only  two  ways  open,  either  not  to  use 
it  or  to  preach  the  sermon  from  the  altar.  In  a  Gothic 
building  of  large  dimensions  the  voice  will  be  more 
distinct  if  the  pulpit  is  placed  in  a  position  where  the 
hearers  may  have  a  chance  to  gather  in  a  large  open 
space. 

Without    the    detailed    plans    of  the    new  Dome 


ACOUSTICS.  63 

building  about  to  be  erected,  I  consider  it  impossible 
to  decide  on  the  most  proper  place  for  the  pulpit,  and 
especially,  as  undecided  problems  cannot  admit  of 
solubility;  the  more  so,  indeed,  if  from  the  beginning 
no  satisfactory  solution  has  been  admitted.  In  general 
it  appears  to  me,  if  the  original  type  of  our  churches 
is  retained,  the  corner  pier  will  be  the  bast,  where  the 
transept  connects  with  the  body  of  the  church.  The 
voice  enters  then  into  the  crossing  divisions  diagon- 
ally, and  at  this  stand-point,  moreover,  is  the  freest 
space.  Still  more  difficult  does  the  problem  become  if 
the  galleries  with  a  terrace-like  arrangement  are  intro- 
duced— for  economical  purposes.  Walls  forming 
divisions  must  then  be  avoided. 

According  to  my  view,  it  would  be  proper  to  make 
on  the  plans  certain  points  at  which  to  place  the 
pulpit  without  infringing  too  much  upon  the  architec- 
tural effect,  and  after  the  building  has  been  sufficiently 
advanced,  to  examine  the  acoustic  effect  of  each,  and 
then  to  select  the  best  place." 

This  last  named  article,  written  by  Dr.  Dove,  is  a 
very  able  and  distinct  synopsis  of  the  past  and  present 
state  of  the  known  theories,  confining  the  sound  rays 
of  speech  and  musical  tones  to  their  limits  and  effects, 
up  to  the  present  day.  All  the  details  given  are,  no 
doubt,  very  precise,  and,  as  generally  established, 
based  upon  science.  Now,  my  readers,  I  have  intro- 
duced this  article  not  alone  owing  to  its  great  interest 
and  value,  but  at  the  same  time  to  form  a  solid  basis 
to  rest  upon,  and  to  prove  how  little  reliance  can  be 


64  ACOUSTICS. 

placed  on  a  theory  of  supposed  causes  and  effects 
which  cfo  not  actually  exist.  We  all  know  that 
there  is  no  certainty  of  constructing  public  buildings 
thus  far  perfect  and  distinct  for  good  hearing ;  and 
yet  clear  and  distinct  speech  in  a  public  building  is 
most  important.  Now,  as  I  stated  before,  a  mere 
accident  led  me  on  to  the  astounding  result,  that  a 
clear  and  healthy  air  is  necessary  to  restore  distinct 
sound  in  a  public  building  where  not  more  than  twenty 
minutes  previous  the  air  was  found  in  a  chaos  of 
mixed  impurities. 

Dr.  Dove  bases  his  experiments  upon  a  medium 
temperature  of  7°  B.  in  Berlin,  and  gives  his  results 
as  to  the  strength  and  effect  of  sound  rays.  This 
may  be  all  very  correct,  but  has  absolutely  nothing  to 
do  with  the  effect  of  sound  in  public  buildings.  The 
Doctor's  experiments  refer  to  the  actual  state  of  the 
outer  temperature  alone,  which  does  not  exist  in  the 
inside  of  a  building.  The  inner  atmosphere,  and  the 
temperature  in  an  occupied  and  inclosed  space,  with- 
out proper  ventilation  changes  every  minute,  and  the 
sound  rays  become  irritated  to  a  degree  fatal  to  dis- 
tinctness. Enough  has  been  said  referring  to  the  spe- 
cific gravity  of  the  different  strata  of  air,  to  prove  how 
the  exhaled  air  affects  the  aerial  space  ;  and  the  diffi- 
culty is  that  the  sound  rays  always  following  the  most 
flexible  air,  become  isolated  or  distinct  in  their  field 
of  operation,  and  hence,  in  this  more  confined  portion 
of  the  aerial  space,  must  naturally  increase  in  force, 
and  create  resounding  effects,  and  become  mixed  and 


ACOUSTICS.  65 

unintelligible.  It  is  perfectly  clear  that  a  certain  force 
concentrated  in  one  spot,  must  have  results  which  will 
materially  differ  when  the  force  is  distributed  ;  does 
not  daily  life  prove  this  assertion  ? 

If  the  sound  rays  are  spread  throughout  an  aerial 
space,  say  in  an  occupied  church,  will  they  act  with  the 
same  force  on  the  curved  ceilings,  or  even  on  the  larg- 
er pillars  ?  Why,  the  strength  of  the  musical  tone  is  a 
proof  of  itself.  There  is  no  difficulty  for  musical  tones 
to  be  heard  more  distinctly  in  any  aerial  space,  owing 
to  their  greater  force  ;  the  force  is  strong  enough  to 
penetrate  into  all  strata  of  air  more  or  less  ;  but  still, 
even  with  this  propelling  force,  the  tones  are  often  di- 
rected to  separate  parts  of  tha  building,  influenced  in 
the  same  manner  by  the  variations  of  the  temperature, 
and  condition  of  the  various  strata  of  air.  The  exam- 
ple and  effects  of  the  variations  of  speech,  and  the  ef- 
fect of  musical  tones,  directly  under  the  dome  of  St. 
Paul's  Cathedral,  in  London,  is  introduced  by  Dr.  Dove 
as  a  most  unmistakable  phenomenon  ;  but  it  must  be 
added,  that  in  this  case  the  difficulty  for  speech  is 
more  than  in  any  other  locality,  as  the  dome  itself  is  a 
condensed  tube  with  an  upward  direction,  carrying 
the  voice  with  it ;  and  it  follows  that  domes  and 
certain  parts  of  ceilings  carried  above  the  general  lev- 
els, will  always  have  a  restraining  influence  in  propa- 
gating sound.  The  effect  of  the  speaker's  voice,  plac- 
ed only  a  few  feet  above  the  level  of  the  floor,  is  lost 
upon  the  gathered  multitude,  and  why?  First,  hu- 
man bodies  deaden  the  sound,  and  the  heavy  strata  of 


66  ACOUSTICS. 

air  which  always  commence  to  accumulate  at  the  floor, 
are  equally  obstructive,  and  it  follows  that  the  floor 
seats  in  a  theatre  or  in  a  church,  are  the  very  seats 
where  you  hear  least  distinctly,  but  the  moment  the 
speaker  takes  a  higher  situation,  say  15  feet  or  even  10 
feet  above  the  level  of  the  floor  (this  means  the  level 
of  his  head  above  the  floor),  the  voice  becomes  more 
distinct.  An  arrangement  to  be  recommended  in  all 
churches  and  public  buildings. 

Now  let  us  take  a  general  view  cri:  all  the  difficulties 
we  have  to  contend  with  in  our  aerial  spaces  to  pro- 
duce clear  sound.  In  fact,  the  difficulties  are  great, 
and  it  is  only  in  this  century  we  begin  to  comprehend 
how  the  sound  rays  move,  and  on  a  retrospective  view 
of  centuries  we  cannot  be  right  in  confining  ourselves 
to  the  attributes  of  sound  only,  such  as  size,  form, 
and  material,  and  by  substituting  external  aerial  effects 
for  those  which  exist  in  the  interior  of  a  public  build- 
ing crowded  with  people,  never !  We  must  ignore  all 
those  difficulties  first,  and  examine  the  condition  of  t'ie 
inner  atmosphere  of  a  crowded  house,  and  then  we 
shall  find  ourselves  in  a  new  field  of  operation.  Who 
can  say  that  a  condensed  air  mass  of  all  kinds  of 
impurities  will  not  affect  the  sound  rays  more  or  less 
in  its  force  to  penetrate  ?  Let  us  hold  on  to  all  the 
forms,  size,  and  materials  which  have  the  tendency  to 
assist  sound  in  its  progress  and  effects,  and  furnish  a 
pure  air  through  ventilation ;  then  sound  will  be  in  its 
natural  element,  and  perform  its  duty.  The  perfect 
chaos  of  theories  introduced  to  assist  sound  have  so 


ACOUSTICS.  67 

far  in  one  sense  actually  been  detrimental  to  any 
advance  in  this  branch  of  science  ;  a  perfectly  repel- 
ling influence  has  been  the  consequence ;  and  how 
could  it  be  otherwise,  with  so  many  theories  presented  ? 

Now,  the  next  question  will  be,  how  can  we  procure 
a  pure  and  healthy  air  in  our  public  buildings  ?  In  an 
auditorium  occupied  with  people,  say  two  hundred 
persons,  allow  four  cubic  feet  of  fresh  air  per  minute 
for  each  individual,  also  the  total  amount  per  second 
2^<4  __  13^  cubic  feet.  It  must  not  be  neglected  that 
the  capacity  of  the  flues  for  escape  of  impure  air 
should  be  at  least  one-fourth  larger  than  the  supply- 
ing flues. 

In  concluding  this  subject,  I  will  here  add,  that  this 
new  discovery  to  gain  intelligible  sound  through  ven- 
tilation, settles  this  fact,  that  sound  depends  princi- 
pally upon  a  clear  and  pure  air  for  intelligible  hear- 
ing, and  is  not  dependent  on  the  attributes  of  form 
and  materials  altogether.  But  the  moment  we  im- 
prison or  inclose  the  sound,  the  sound  becomes  imme- 
diately restrained  by  form  and  materials  in  its  natural 
action,  and  proper  form  and  materials  become  a  ne- 
cessity to  guide  the  sound  rays  to  their  proper  chan- 
nel and  extent,  with  proper  clearness.  And  as  this 
application  has  not  been  sufficiently  attended  to,  fail- 
ure has  been  the  result. 


68  HEATING   AND   VENTILATION. 


GENERAL   VIEWS   OF   HEATING   AND   VENTILATION. 

Ventilation  has  not  yet  arrived  at  perfection  to  a 
point  of  mathematical  precision  ;  but  this,  although 
desirable,  is  not  absolutely  necessary.  Heating  and 
ventilation  are  branches  of  science  which  have  re- 
ceived thus  far,  a  general  acknowledgment,  embodying 
principles  of  the  greatest  importance;  but  the  applica- 
tion of  those  principles  for  practical  purposes  has 
proved  insufficient.  How  pressing  this  deficiency  has 
been  felt,  is  proved  by  the  various  experiments  intro- 
duced, even  on  the  largest  scale  ;  thousands  of  dollars 
have  been  expended  to  gain  the  point  of  a  healthy  cir- 
culation of  air,  in  some  cases  with  more,  in  others 
with  less  success. 

Now,  let  us  trace,  from  those  many  experiments, 
and  their  failures,  the  truth  of  the  above  assertions. 
All  the  appliances,  either  natural  or  artificial,  to  gain 
a  healthy  circulation  of  air  have  proved  insufficient, 
and  this  fact  leads  to  another  important  one,  that  the 
atmosphere  with  direct  and  indirect  influences  has  not 
been  properly  understood,  or  else  the  appliances 
would  have  been  different. 

What  fault  can  we  find  with  the  present  systems  of 
ventilation  and  heating  ?  Why,  the  fault  is  this : 
Public  buildings  have  been  only  partially  ventilated 
and  heated,  and  the  air  contained  in  them  revolu- 
tionized more  or  less,  without  regard  to  the  natural 
consequences  arising  from  such  arrangements.  What 


HEATING  AND  VENTILATION.  69 

constitutes  a  perfect  ventilation  ?  Nothing  more  than 
a  moderate  and  equal  temperature  throughout  every 
part  of  the  building,. consisting  of  a  fresh  and  healthy 
air  in  a  continued  flow  of  supply  and  proportionate 
escape  without  any  perceivable  motion.  The  air  con- 
tained in  a  building,  especially  when  filled  with  people, 
is  in  a  continued  state  of  chemical  mixture ;  yes,  the 
materials  of  the  surrounding  walls,  ceilings,  etc.,  have 
their  influences  likewise,  and  this  chaos  of  influen- 
cing matter  is  to  be  removed,  or  the  air  cannot  be 
healthy,  and  those  same  influences  lead  sound  to  its 
natural  grave. 

I  will  here  introduce  an  example  given  by  "  Dr.  J. 
Berger,"  to  prove  how  variously  the  temperature  of  air 
confined  in  a  room  heated  by  a  stove  is  affected,  and 
at  the  same  time  give  a  clear  view  of  the  present  sys- 
tem of  modern  heating. 

"In  a  room  20  feet  long,  10  feet  in  width,  and  11 
feet  high  is  placed  a  cast  iron  stove,  near  one  of  the 
corners,  immediately  opposite  a  window  on  the  longi- 
tudinal side  of  the  room. 

"  By  an  outer  temperature  of  2°  E.,  a  thermometer 
protected  against  the  morning  rays  of  the  stove  showed 
the  following  result : 

At  the  floor.  At  the  ceHing.  Loss. 

1'  distance  from  window    10°5 19° 8°5 

At  the  middle  of  the  room  11°    20°5 9°5 

I'  distance  from  the  stove  12°   23° 11° 

"  This  proves  that  the  air  of  the  lower  part  of  the 


70  HEATING  AND  VENTILATION. 

room  towards  the  floor  has  about  half  as  many  de- 
grees E.,  as  the  air  at  the  higher  par&.  You  will  read- 
ily notice  the  immense  loss  of  actual  warm  and  service- 
able air  to  the  inmates.  The  healthy  remedy  general- 
ly acknowledged  to  keep  the  head  cold  and  the  feet 
warm,  could  not  be  applied  with  such  a  conflicting 
temperature.  On  the  contrary,  the  head  in  its  natu- 
ral position  would  be  warm  and  the  feet  cold.  This 
process  of  heating  by  the  stove,  applies  more  or  less  to 
all  heating  methods  now  in  use,  as  every  one  of  them 
leads  the  warmer  air  to  the  ceiling  of  any  room  or  hall 
etc.,  allowing  the  heat  in  the  downward  march  to  be 
absorbed  by  the  windows,  walls,  etc.,  and  scarcely 
warming  the  lower  cold  strata  of  air  where  most  need- 
ed ;  and  in  this  lower  strata  is  the  resting  place  of  the 
organic  impurities  caused  by  the  exhaled  air,  evapora- 
tions, etc.,  producing  the  actual  poison  which  the  lungs 
detest,  and  sound  abhors.  No  mode  is  hitherto  known 
of  measuring  those  mixed  quantities  of  impurities 
in  the  air  with  precision.  To  come  to  any  near  ap- 
proximation, we  must  first  calculate  the  amount  of  car- 
bonic acid  contained  in  the  air,  and  allow  that  the 
quantum  of  the  organic  impurities  are  proportional  to 
it.  The  next  point  will  be  to  confine  the  carbonic  acid 
as  represented  by  the  most  able  searchers  into  the  va- 
rious methods,  and  with  the  general  result,  to  prove 
that  the  substance  and  quantity  of  the  carbonic  acid 
is  to  be  found  in  the  upper  parts  of  an  inhabited  room 
to  a  much  greater  degree  than  in  the  lower.  The 
cause  is  as  plain  as  important.  The  lower  part  of  the 


HEATING  AND  VENTILATION.  71 

air  becomes  warmed  through  the  bodies,  and  rises 
with  the  mixture  of  impurities,  and  at  a  higher  point 
follows  the  draft  to  colder  parts  of  the  room,  and  sinks 
mixed  with  fresh  air,  penetrating  through  the  pores 
and  smaller  crevices  somewhat  diluted,  to  unite  again 
with  the  organism.  If  it  were  possible  to  stop  this 
downward  movement,  and  carry  off  this  impure  air  af- 
ter rising,  out  of  the  room,  then  the  carbonic  acid 
substance  would  never  be  noticed,  no  matter  how 
large  the  assembly  of  people,  or  how  strong  the  gas- 
light might  be  ;  but  as  the  impure  air  will  ever  repeat 
its  downward  movement,  so  it  will  repeatedly  enter  the 
lungs  and  affect  the  system  most  dangerously."  Here 
is  the  boundary  where  words  must  become  deeds  ;  this 
sickening  air  must  be  driven  away  without  mercy,  and 
then  we  shall  have  arrived  at  a  point  to  benefit  the  hu- 
man race  ;  health  and  acoustics  will  shake  hands,  and 
public  buildings  will  become  a  focus  of  pleasure  and 
attraction  ;  many  valuable  lives  that  adorn  the  pulpit 
will  be  saved  from  their  early  graves.  How  many 
children  who  are  now  prisoners  in  the  unhealthy  strata 
of  school  air,  for  a  number  of  years,  and  return  to 
the  new  paths  of  life  diseased,  will,  when  all  the  evils 
have  vanished,  return  in  a  healthy  and  vigorous  state 
to  practical  life. 

Now,  we  should  suppose  a  speedy  remedy  could  be 
found  to  overcome  the  above-mentioned  evils,  but  let 
us  not  be  too  sanguine  ;  it  will  not  be  found  for  some 
time  to  come  —  not  until  every  person,  or  at  least,  a 
large  number  of  an  intelligent  class  shall  become  fa- 


72  HEATING  AND  VENTILATION. 

miliar  with  this  branch  of  science  ;  then  architects  and 
doctors  will  be  forced  to  fall  into  line  like  the  soldier 
into  the  line  of  battle,  not  to  destroy,  but  to  rescue 
valuable  life.  So  it  is  with  art ;  is  it  ever  acknowl- 
edged, without  a  general  knowledge  and  appreciation  ? 
Let  us  hope  that  the  time  will  soon  come  when  science 
will  assist  and  guide  us  to  our  duties.  It  was  not  my 
plan  at  first  to  enter  into  the  details  of  ventilation. 
My  intention  was,  to  give  a  general  view  only  of  the 
present  mode  of  heating  and  ventilation,  and  to  draw 
attention  to  the  want  of  its  proper  application,  so  far 
as  in  my  power,  but  a  few  days  ago  I  received  a  new 
work  on  heating  and  on  ventilation,  by  Dr.  J.  Berger, 
written  in  the  German  language,  which  gives  many  il- 
lustrations and  suggestions,  and  with  such  clearness  and 
adaptation  to  the  purpose,  that  I  thought  it  best  to  in- 
troduce some  of  them,  with  the  hope  that  they  may  in- 
terest the  public  upon  that  important  branch  of  sci- 
ence: 

"  As  soon  &s  a  stove,  placed  in  a  room,  begins  to 
throw  out  heat,  so  soon  the  former  perfectly  calm  air 
will  be  drawn  into  a  most  lively  and  disturbed  move- 
ment, and  this  movement  you  may  readily  notice  by 
placing  yourself  before  a  window ;  a  sensible  cold  air 
draft  will  meet  you,  no  matter  how  perfectly  the  windows 
are  closed  ;  this  cold  air  draft  commences  whenever  the 
heating  begins,  and  it  cannot  be  denied  that  it  has 
originated  from  the  interior  of  the  room.  Now,  to  il- 
lustrate more  clearly  this  singular  movement,  let  us 
t&ke  the  most  simple  method  of  tracing  it  with  a  small 


HEATING   AND   VENTILATION.  73 

piece  of  burning  tinder.  Hold  this  burning  tinder 
near  the  stove,  and  the  smoke  will  rise  on  the  sides 
and  on  the  edge  of  the  projecting  top  cover,  but  in  the 
middle  of  the  cover  it  becomes  restrained,  and,  unad- 
justed, is  driven  back  to  the  edge  of  the  cover,  and 
from  thence  it  rises  again.  If  you  hold  the  tinder 
somewhat  higher  above  the  top  of  the  cover,  then  the 
smoke  will  partially  rise  and  fall  towards  the  middle. 
"  These  simple  experiments  give  us  an  insight  to  the 
previous  examples.  It  is  evident  that  the  air  is  drawn 
from  around  the  stove  to  the  stove  itself,  then  becomes 
heated,  and  rises  upwards  in  a  lively  upward  current 
on  all  sides  ;  but  it  is  equally  evident  that  the  heated  air 
above  the  cover  will  be  dislodged  and  replaced  by  the 
hither  flowing  cold  air.  But  the  colder  air  can  only 
flow  from  the  direct  neighborhood  of  the  stove,  and 
naturally  must  intercept  the  flow  of  air  which  has  been 
rising  on  the  sides  of  the  walls  at  different  places,  often 
changed  and  precipitated  upon  the  middle  of  the  cov- 
er ;  it  then  becomes  heated  and  rises,  and,  pressed  on 
the  upward  flowing  air,  is  immediately  carried  with  it 
in  close  proximity  to  the  edges  of  the  cover.  Further 
above  the  cover,  where  the  colder  air  ceases  to  sup- 
ply, only  an  upper  current  of  air  takes  place,  and  the 
smoke  of  the  tinder  above  the  cover  is  carried  upwards, 
and  its  course  can  be  traced  to  the  ceiling  of  the  room. 
This  will  occur  in  a  similar  manner  with  larger  heat- 
ed surfaces.  If  we  notice  the  course  of  the  ascending 
air,  and  observe  the  direction  in  which  the  smoke  of 
the  burning  tinder,  placed  at  various  parts  of  the  room 


74  HEATING  AND  VENTILATION. 

is  forced,  it  is  easily  perceived  that  from  the  tipper 
parts  of  the  stove  the  main  flow  is  toward  the  win- 
dows and  the  colder  walls  of  the  room,  and  from 
thence  in  a  sinking  condition  again  retraces  its  steps 
i  towards  the  lower  parts  of  air  surrounding  the  stove. 
By  lifting  the  burning  tinder  in  one  part  of  the  room 
gradually  higher,  you  will  notice  how  the  smoke  is 
stronger  below ;  but  the  higher  above,  the  weaker  it 
is  driven  towards  the  stove,  till  the  smoke  at  last  rises 
perpendicularly  ;  however,  it  soon  changes  its  course 
in  the  reverse  direction.  On  the  walls  near  the  stove, 
where  they  are  somewhat  heated,  the  air  does  not  de- 
scend, but  rises  naturally  upwards.  This  illustrated 
rotary  movement  bases  itself  upon  the  very  plainest  of 
fundamental  laws.  This  law  is  the  following  :  The 
heavier  liquid  always  falls  to  the  lowest  spot.  The 
air  cooled  by  the  windows  and  walls  contracts  by  this 
influence,  and,  with  an  addition  to  its  specific  weight, 
sinks  to  the  floor  and  presses  the  warmer  air  upward, 
and  in  such  a  manner  that  the  higher  it  is  placed,  the 
higher  the  temperature  is  marked  in  the  thermometer. 
"  Near  the  stove  the  air  receives  its  progressive  move- 
ment to  the  highest  temperature.  As  soon  as  the  air 
becomes  warm,  that  moment  it  is  pressed  by  the  ad- 
joining cooler  air,  upwards,  and  then  flows  to  the  more 
distant  parts  ;  and  in  one  place  the  cooled  and  specifi- 
cally heavier  air  is  continually  pressed  downwards,  and 
at  another  place,  the  warmer  and  lighter  air  is  contin- 
ually carried  upwards,  and  so  the  rotary  movement 
takes  place  consistently  with  the  law  of  nature.  But  it 


HEATING  AND  VENTILATION.  75 

is  not  to  be  understood  by  this  that  the  heated  air 
possesses  an  inward  natural  tendency  to  rise,  and  that 
this  tendency  is  really  the  originating  power  to  cause 
the  movement.  This  very  mistaken  idea  seems  to 
have  been  the  cause  of  many  errors  of  the  past,  and 
has  led  to  many  costly  experiments.  The  greater  the  dif- 
ference of  temperature  between  the  several  air  masses, 
the  more  energetical,  and  the  more  quickly  successive 
the  rotary  movement  will  be.  It  is  known  that  the  air 
in  a  gassy  condition  dissolved  contains  more  moisture 
the  higher  the  temperature,  and  that  the  heated  air 
withdraws  the  moisture  from  the  walls.  After  the  air 
has  been  in  a  considerable  degree  cooled  down,  then 
it  is  forced  to  submit  to  the  laws  of  its  moisture,  as  the 
cooling  process  deprives  it  of  the  dissolving  quality, 
and  so  the  windows  become  covered  with  it.  In  a 
room  where  the  moisture  is  increased  by  cooking, 
washing,  and  by  exhaled  air,  etc.,  the  moisture  settles 
on  the  cooler  parts  of  the  walls,  particularly  behind 
beds,  wardrobes,  etc.,  and,  as  the  moisture  possesses 
mixtures  of  other  substances,  the  more  it  is  to  be  com- 
prehended that,  in  this  condition,  ample  cause  is  given 
for  a  mouldy  and  putrefying  process.  It  is  an  error  to 
open  occasionally  the  door  of  an  adjoining  cold  bed- 
room, rarely  ever  aired ;  there  the  moisture  begins 
to  form  its  malignant  effect  on  health.  In  such  rooms 
fungi  are  formed,  and  a  whole  family,  who  occupied 
one  of  those  rooms  at  night,  during  a  whole  winter, 
were  reduced  to  a  most  lamentable  state  of  health. 
The  people  cannot  be  warned  enough  against  such 


76  HEATING  AND  VENTILATION. 

mistakes,  particularly  from  the  evil  effects  not  showing 
themselves  directly;  they' are,  on  this  very  account, 
more  dangerous." 


MODERN    VENTILATION. 

All  the  phenomena  referring  to  this  subject  may  be 
traced  more  or  less  to  the  movements  of  water  on  the 
principle  of  communicating  pipes.  For  instance,  if 
two  perpendicular  pipes  are  connected  by  another  in  a 
cross  direction,  and  filled  with  fluid,  for  example, 
water,  then  the  water  will  rise  in  both  of  them  to  an 
equal  height.  If  different  fluids  are  poured  in,  then 
the  height  of  the  fluids  will  be  inversed  according  to 
their  specific  weight.  If  the  liquids  are  quicksilver 
and  water,  the  quicksilver  in  one  of  the  pipes  will,  for 
example,  be  one  foot,  and  the  water  in  the  other  will 
stand  14  feet  high ;  and  it  is  of  no  consequence 
whether  the  two  upright  pipes  are  equal  in  size  or 
different.  If  we  take  it  for  granted  that  one  pipe  is 
only  one  foot,  but  the  other  15  feet  long,  if  the  latter 
pipe  is  continually  filled,  the  water  in  the  short  pipe 
would  break  forth  to  the  corresponding  level  of  15  feet, 
and  it  certainly  would  gain  this  height  if  its  flexibility 
did  not  produce  a  considerable  diminution.  There 
are  two  causes  which  take  the  advantage  of  the  flexi- 
bility. The  one  is  the  weight.  This  weight  draws  the 
rising  water  parts,  the  higher  they  are  the  most  en- 
ergetically backwards,  consequently  the  upper  parts 
will  always1  rise  more  slowly,  and  prevent  the  lower 


HEATING  AND  VENTILATION.  77 

from  a  quick  upward  movement,  and  with  a  pressure 
causing  the  parts  to  shift  to  a  sideward  direction.  So 
the  water  jet  spreads  out  upwards  in  a  conical  form, 
and  loses  in  height  whatever  it  gains  in  the  transverse 
section.  The  second  cause,  the  resistance  of  the  air, 
operates  similarly,  and  this  force  parts  the  rays  pos- 
sessed with  the  natural  tendency  to  the  formation  of 
drops,  and  assists  them  in  innumerable  parts  to  a  re- 
peated downward  fall.  The  lighter  the  rising  fluid  the 
less  the  influence  of  weight;  the  influence  of  resistance 
however  is  greater,  to  which  we  must  bestow  our  most 
particular  attention.  If  we  place  a  pipe  one  foot  in 
length  in  a  high  wash-bowl,  and  fill  it  with  spirits  of 
wine,  which  is  lighter  than  water,  but  heavier  than  air, 
and  let  the  water  rise  through  the  spirits,  the  resist- 
ance would  be  still  greater.  We  should  notice  the 
rising  stream  easily,  and  should  be  able  to  discern  it 
more  distinctly  by  its  coloring  the  water,  and  then  we 
should  notice  that  the  jet  of  water  upwardly  would 
spread  quickly,  and  by  no  means  rise  as  high  as  for- 
merly in  the  air.  If  we  allow  the  jet  of  water  to  play 
some  time,  then  the  spirits  of  wine  becomes  more 
watery,  heavier,  the  jet  wider  and  lower,  till  at  last, 
dissolved  on  the  bottom,  it  becomes  immovable.  The 
more  compact  the  middle  in  proportion  to  the  liquid, 
which  moves  in  an  ascending  stream  within,  the  more 
it  spreads,  and  the  nearer  to  the  bottom.  All  the  facts 
alluded  to  above  will  assist  and  enable  us  now  to  a 
clear  conception  of  the  former  remarks  in  our  system 
of  ventilation.  A  very  effective  and  plain  ventilation 


78  HEATING  AND  VENTILATION. 

may  be  gained  at  a  trifling  expense  in  rooms  where  no 
calculation  for  ventilation  has  been  made.  At  any 
point  in  a  room  wherever  a  good  connection  with  the 
outer  atmosphere  can  be  made,  place  a  pipe  of  tin  or 
of  any  other  material,  several  feet  long,  perpendic- 
ularly, and  inserted  in  the  floor,  with  elbow  at  the 
lower  end  to  connect  with  the  outer  air,  the  pipe  or 
pipes  to  have  both  ends  open ;  let  their  diameter  be 
two  or  three  inches,  somewhat  in  proportion  to  the 
room  ;  in  a  small  room  only  one  inch  diameter.  As 
soon  as  the  room  is  heated,  no  matter  in  what  manner, 
the  outer  air  enters  the  pipe,  but  does  not  sink  into 
the  lower  strata  of  air  contained  in  the  room,  but  rises 
with  increased  rapidity  in  proportion  to  the  increase 
of  heat.  If  you  enter  in  very  cold  weather  into  such 
a  heated  room,  you  will  notice  a  powerful  air  draft, 
even  at  a  considerable  distance  in  height,  and  by 
placing  the  hand  on  the  inner  opening  of  the  pipe  it 
is  pressed  upwardly  with  great  force.  If  we  place 
a  short  pipe  in  the  ceiling  of  the  room,  and  con- 
nect it  with  the  outer  air,  the  effect  will  not  be 
changed;  we  shall  find  precisely  the  same  result  as 
with  the  other  arrangements.  In  place  of  the  water 
we  have  the  cold  air ;  in  place  of  the  spirits  of  wine 
we  have  the  warmer  and  lighter  air  of  the  room  or 
saloon,  in  which  the  cold  air  penetrates  through  the 
short  pipe.  If  the  room  should  be  empty  of  air,  then 
the  air-jet  would  spring  to  the  ceiling.  The  greater 
the  difference  of  the  outer  and  inner  temperature,  the 
nearer  we  approach  this  case,  and  the  lesser  the  resist- 


HEATING  AND  VENTILATION.  79 

ance,  the  higher  in  proportion  rise  the  rajs  over  the 
heads  of  the  inmates.  A  water-jet  always  returns  to 
the  earth,  but  it  is  different  with  the  rising  air-jet. 
The  more  it  comes  in  contact  with  the  dissolving 
warmer  air,  the  more  quickly  it  receives  the  warmer 
temperature,  and  the  more  quickly  also  vanishes  the 
tendency  to  descend.  The  entering  fresh  air  steps  into 
the  circular  sphere  of  the  existing  impure  atmosphere ; 
one  part  of  the  mixed  air  escapes  through  an  opening  at 
the  ceiling.  It  is  noticed  that  the  greater  the  difference 
of  temperature  between  the  inner  and  outer  air,  the  less 
the  inmates  gain  by  the  entering  fresh  air,  notwithstand- 
ing the  greater  influence  of  the  cooling  process.  The 
higher  the  saloon  is,  the  farther  in  height  reaches  the 
difference  of  temperature  between  the  inner  and  outer 
air ;  the  higher  also  you  calculate  the  outer  pipe  to  be, 
the  higher  will  ascend  the  rays  of  fresh  air. 

From  the  preceding,  it  follows,  what  opinion  we  may 
form  of  another  application  that  has  often  been  made. 
Basing  upon  experience,  that  the  air  in  the  upper  parts 
of  a  heated  room  is  warmer  than  in  the  lower,  open- 
ings have  been  inserted  in  the  walls  close  to  the  floor, 
to  allow  the  impure  air  to  escape  with  as  little  loss  of 
heat  as  possible.  That  the  lower  air  of  a  room  is  cool- 
er than  the  upper  is  certain,  but  it  is  equally  certain 
that  the  outer  atmosphere  is  still  more  so,  and  natu- 
rally the  one  enters  through  the  flues  inwardly,  while 
the  other  passes  outwardly.  This  and  similar  arrange- 
ments lead  to  that  great  fundamental  error.  The  heat 
is  furnished  to  the  upper  parts,  whereas  the  intention 


80  HEATING  AND  VENTILATION. 

and  desire  is  to  use  it  at  the  lower.  All  the  impuri- 
ties of  the  air  wander  inseparably  with  the  heat ;  to 
restrain  and  let  them  escape  from  the  higher  strata  of 
the  room,  has  been  unsuccessfully  attempted.  To  at- 
tain the  first  point  actually,  the  second  is  gained,  and 
to  attain  the  latter  you  infringe  on  the  other.  The 
Doctor  says,  in  a  large  saloon  in  Frankfort,  a  large  flue 
was  constructed,  with  an  opening  of  5  or  6  feet  from 
the  ceiling.  Through  this  flue  it  was  intended  the 
warm  and  impure  air  should  escape  to  the  outer  at- 
mosphere ;  but  the  very  reverse  movement  took  place, 
and  the' cold  air  rushed  into  the  saloon  with  such  ve- 
hemence that  the  draft  had  to  be  stopped  immediate- 
ly. In  the  Hospital  La  Biboisiere  at  Paris,  the  cold 
air,  with  the  same  arrangements,  poured  into  one  of 
the  wards,  notwithstanding  the  fresh  air  was,  in  great 
quantity,  forced  in  by  a  machine.  Now  let  us  be  clear 
on  these  proceedings.  If  we  fill  a  glass  with  water, 
and  fill  a  small  pipe  with  quicksilver,  and  expect  that 
the  water  will  raise  the  quicksilver,  and  then  the  quick- 
silver rise  of  itself,  everybody  would  at  once  wonder  at 
such  a  demand  ;  in  one  case  the  quicksilver  and  in  the 
other  the  heavy  air  descends  towards  the  bottom,  and 
the  water  pressed  upwards  will  overflow  in  the  same 
manner  as  the  lighter  air  is  carried  higher  in  the  sa- 
loon. Should  it  be  desired,  however,  to  let  the  air  es- 
cape through  the  flue  under  the  ceiling,  then  it  would 
be  necessary  to  heat  this  flue  still  higher  than  the 
temperature  of  the  hall.  But  what  would  be  the  re- 
sult if  a  flae  was  to  be  extended  inside  the  wall  to  the 


HEATING  AND  VENTILATION.  81 

floor  and  heated  as  it  is  often  done?  It  is  evident 
that  the  air  rising  from  the  stove,  and  with  it  its  im- 
purities, descends  again  and  repeatedly,  to  reach  the 
opening  of  the  flue,  and  the  impurities.,  or  at  least  a  part 
of  them,  will  again  enter  through  the  lungs.  There  ap- 
pears now,  from  the  former  mentioned  case  in  which 
the  cold  air  descends  to  the  bottom,  and  from  the  one 
preceding,  in  which,  under  similar  circumstances,  tho 
flow  or  current  is  upwards,  to  be  a  contradiction  in  itself. 
This,  however,  is  only  apparently  so.  If  the  flue  with 
an  outlet  5  or  6  feet  below  the  ceiling  of  the  saloon 
had  been  extended  to  the  floor,  then  the  air,  by  suffi- 
cient difference  of  temperature,  would  have  been  equally 
vehement  in  rising,  but  would  not  descend.  In  the 
first  case,  the  descending  air  follows  the  law  of  weight, 
the  same  as  dropping  water ;  liquid  bodies  spread  all 
over  the  bottom  and  press  the  extended  aerial  masses 
higher.  In  the  second  case  the  air  follows  likewise 
the  law  of  weight ;  it  cannot  spread  apart  at  the  bot- 
tom of  the  flue  ;  it  must,  by  the  assistance  of  the  pres- 
sure of  its  additional  weight,  force  the  lighter  columns 
of  air  higher.  But  this  is  not  the  warmer  air  of  the 
saloon,  it  is  the  former  descending  cold  air  ;  it  is,  how- 
ever, now  concentrated  from  the  former  field  of  action, 
and  the  whole  pressure  acts  upon  the  transverse  sec- 
tion of  the  ascending  flues.  If  the  cold  air  had,  for 
example,  covered  the  whole  extent  of  the  saloon 
floor,  1,000  square  feet,  one  foot  high,  the  adjoining 
warm  air  would  have  been  forced  up  one  foot  higher 
also ;  and  if  the  height  of  the  saloon  had  not  exceeded 


82  HEATING  AND  VENTILATION. 

ten  feet,  10,000  cubic  feet  of  air  would  have  been 
forced  upward  one  foot.  And  notwithstanding  the 
transverse  section  of  the  perpendicular  ascending  flue 
should  contain  only  one  square  foot,  10,000  cubic  feet 
of  air  would  have  been  raised  one  foot  in  the  same 
time.  The  laws  of  nature  are  infallible ;  if  parts 
of  a  mass  can  move  without  obstruction,  they  certainly 
will  regulate  themselves  according  to  their  weight;  the 
heaviest  will  seek  the  lowest,  and  the  lighter  by 
degrees  higher  positions.  Besting  upon  this  law,  we 
are  accustomed  to  see  the  ascending  air  from  the 
stove.  This  is  really  the  case,  provided  this  law  has 
its  fair  field  to  operate  upon  ;  if  not  it  will  fail.  The 
Doctor  gives  here  an  example  of  a  Foundling  Asylum. 
The  building  is  two  stories  in  height,  and  to  supply 
fresh  air  in  the  second  story  wards  a  hexagon  tower 
was  constructed  over  the  roof,  from  which  four  hori- 
zontal air  channels  or  flues  were  placed  in  connection 
with  the  tower,  and  extended  under  the  roof,  with  an 
outlet  very  ingeniously  arranged  to  receive  the  outer 
atmosphere.  With  those  flues  large  canals  were 
connected  with  the  basement,  and  from  them  branch 
canals  led  the  air  to  the  first  and  second  stories  to 
supply  circular  cast-iron  stoves  surrounded  with 
chambers  to  receive  the  cold  air  for  heating  purposes, 
similar  to  our  furnace  arrangements.  The  most 
particular  examination  has  given  the  following 
results :  Nearly  one-half  of  the  movements  proved 
unfavorable ;  one-sixth  part  entirely  contrary  to 
that  required.  The  difficulty,  it  is  stated,  gener- 


HEATING  AND  VENTILATION.  83 

ally  took  place  at  night,  whenever  a  brisk  wind 
arose  from  any  direction.  The  very  reverse  move- 
ment to  that  required  was  so  strong,  that  the 
wards  often  became  very  cold,  and  in  the  flues  the 
temperature  of  30°  was  noticed.  Now  let  us  place 
this  arrangement  before  us  on  a  smaller  scale,  which 
may  easily  be  done.  Two  perpendicular  upright  stove 
pipes  communicate  and  connect  at  the  lower  ends  by  a 
short  horizontal  pipe.  In  this  last  named  pipe  hot 
coals  are  placed,  so  that  the  nearest  adjoining  upright 
pipe  is  heated;  and  let  us  call  the  heated  pipe  the  hot, 
and  the  other  the  cold.  A  lively  cold  air  stream  will  en- 
ter the  latter,  and  an  equally  lively  warm  one  will  escape 
from  the  first.  By  blowing  inwardly  into  the  hot  pipe 
the  flow  will  be  reversed  in  the  one  inwardly,  and  out- 
wardly from  the  other.  If  the  blowing  is  stopped,  a 
moment's  pause  will  take  place,  and  then  the  flow  will 
return  to  its  original  course.  By  making  the  cold  air 
pipe  smaller  than  the  hot,  then  the  reverse  movement 
is  less  likely  to  take  place  ;  the  greater  the  difference 
of  the  longitudinal  section,  even  should  the  cold  air 
pipe  be  extended  to  twice  or  three  times  the  length  of 
the  hot,  if  you  blow  into  the  latter  a  reversed  move- 
ment will  quickly  follow,  the  more  so  the  longer  the 
cold  air  pipe  is ;  the  moment  we  stop  blowing,  this 
flow  will  with  less  facility  return,  and  will  with  more 
energy  persist  the  longer  in  it  the  longer  the  pipe  is. 
Should  we  make  the  cold  pipe  shorter  than  the  hot,  or 
insert  an  opening  at  the  bottom  of  it,  the  return  of  the 
proper  movement  would  take  place.  It  is  also  easily 


84  HEATING  AND  VENTILATION. 

comprehended  that  the  return  may  be  gained  by 
blowing  into  the  cold  pipe,  and  it  is  also  easy  to  givo 
an  account  of  the  proceeding.  The  air  expands  with 
each  degree  of  heat  0.00366  of  its  volume.  If  heated 
to  100°,  then  its  volume  will  increase  about  one-third 
more  than  in  its  former  state.  If  the  two  pipes  con- 
tained an  equal  volume  of  air,  then  they  must  have  an 
equal  height;  and  if  the  one  is  heated  to  100°,  then  the 
one-third  of  its  air  is  naturally  warmer  than  the  whole 
volume  of  the  other;  consequently  the  latter  is  pressed 
out,  the  colder  air  enters  the  hot  air  pipe,  becomes 
equally  warm,  and  meets  with  the  same  fate  as  the  for- 
mer air  that  was  pressed  out.  If  we  blow  into  the  hot 
air  pipe,  then  the  heat  is  carried  from  that  pipe  to  the 
horizontal  piece,  and  to  the  cold  air  pipe,  and  as  a  mix- 
ture takes  place,  it  is  plain  that  in  the  cold  pipe  the 
heat  cannot  be  as  great  as  in  the  hot,  notwithstanding 
the  flow  of  hot  air ;  the  return  is  easily  possible,  par- 
ticularly if  the  cold  pipe  is  smaller.  Should  the  latter 
be  double  the  length,  then  it  will  contain  two  volumes 
of  air  with  a  heat  of  100°  with  f  loss,  and  the  loss  of 
heat  in  the  short  piece  proves  itself  IB  significant.  It 
follows,  now,  that  the  upper  volume  of  air  in  the  short 
heated  pipe  will  use  its  pressure,  the  outer  the  same 
as  the  inner ;  consequently  two  volumes  press  against 
1|  volume.  A  voluntary  turning  is  not  possible  to  take 
place.  If  we  open  the  cold  air  pipe  near  the  bottom, 
or  shorten  it,  then  the  cold  air  will  flow  in,  the  warm 
air  column  will  be  less,  and  an  inversion  will  take 
place.  The  more  easily  the  pipes  can  be  heated,  the 


HEATING  AND  VENTILATION.  85 

bstter  conductors  of  air  they  will  be,  and  the  more  dis- 
criminating will  easily  connect  the  phenomena  with 
the  observation.  The  shorter  piece  may  play  a  very 
important  part.  The  longer  it  is,  the  more  difficult 
will  be  the  return.  There  is  not  only  a  restraint  by 
the  admissibility  of  heat,  but  also  by  the  friction 
affecting  the  inner  passing  flow  of  air.  By  canals  or 
sewers  below  the  streets  in  which  the  draft  of  air  is 
under  the  same  influence  of  the  laws  demonstrated, 
this  vertical  pipe  is  to  be  compared  with  the  sewer 
itself ;  if  very  long  or  extensive,  this  influence  is  great. 
It  is  not  necessary  to  mention  again  the  case  referred 
to,  that  of  supplying  the  stoves  in  the  Hospital  wards 
with  cold  air.  What  we  gain  by  blowing  inwardly  can 
in  the  other  case  be  effected  in  various  ways,  some- 
times under  favorable  circumstances  by  closing  a  door. 
Whenever  a  strong  wind  blew  into  the  tower,  and 
consequently  into  the  wards,  a  reverse  shock  towards 
the  tower  had  to  follow,  similar  to  the  effect  of  a 
strong  wind  upon  an  inward  folding  window  partly 
open.  With  a  great  heat  in  the  stoves,  the  return 
movement  naturally  took  place,  and  it  would  have 
occurred  much  oftener  had  the  tower  been  more  ele- 
vated above  the  level  of  the  stoves,  or  the  warm  air 
columns  supposed  to  be  extended  to  the  ceiling  of  the 
saloon.  This  example  proves  that  the  ventilation  in 
the  wards  of  the  first  story  was  worse  than  in  the 
second.  The  flues  or  canals  referred  to  in  the  Hospital, 
which  connected  with  the  two  stories  and  communi- 
cated together,  would  naturally  have  caused  an  over- 


86  HEATING  AND   VENTILATION 

flow  of  bad  air  from  one  story  to  the  other.  The 
flues  from  the  basement  to  the  ceiling  of  the  second 
story  were  larger  than  those  to  the  first ;  it  follows, 
therefore,  that  the  flow  of  air  from  the  first  to  the 
second  story  was  more  easy  than  to  a  reverse  move- 
ment. The  latter  movement  could  only  be  produced 
by  the  heat  in  the  first  story  being  strong,  and  in  the 
second  much  milder.  It  is  equally  as  easy  to  demon- 
strate that  the  northern  half  of  the  building  is  more 
calculated  to  assist  the  functionary  movement  than 
the  exposure  of  the  southern  half  a  whole  day  to  the 
sun,  as  that  the  whole  arrangement  proved  less  satis- 
factory in  the  hottest  part  of  the  day.  We  see,  there- 
fore, from  the  aforesaid,  that  the  whole  error  of  the 
arrangement  consists  in  this,  that  the  cold  air  has  been 
conducted  from  the  highest  point  with  much  cost, 
whereas  it  should  have  been  drawn  from  a  deep  place, 
and  with  less  cost.  The  mistake  could  have  been 
remedied  in  a  simple  way,  viz.,  by  shutting  up  the 
upper  arrangement,  and  by  constructing  a  cold  air  flue 
from  the  basement  descending  towards  the  garden, 
where  the  flow  would  have  been  inwardly  at  all  times, 
and  the  warm  air  would  never  have  suffered  any  loss. 
The  idea  to  lead  the  fresh  air  upwards  from  a  hot 
stove,  as  was  the  case  in  the  Hospital,  appears  on  first 
sight  impractical,  but  with  a  closer  inspection  it  is 
found  otherwise.  By  the  former  example  before  men- 
tioned it  is  explained  how  the  cold  air  is  driven  up- 
wards in  the  warm  saloon,  and  it  follows  hence  that 
we  should  take  notice  practically  of  the  ascending 


HEATING  AND  VENTILATION.  87 

rays.  The  heated  air  masses  near  the  stove  are  the 
hottest  in  the  whole  saloon,  and  even  without  the  outer 
pressure  the  upward  flow,  on  account  of  its  higher 
temperature,  will  rise  to  the  highest  points  of  the 
saloon.  But  the  greater  the  difference  of  tempera- 
ture between  the  inner  and  outer  air,  the  more  ener- 
getical will  be  the  ascending  movement.  If  there  is  a 
number  of  openings,  as  there  should  be,  placed  at  the 
highest  points  for  escape,  then  it  is  clear  that  the 
newly  entered  good  air  escapes  without  any  benefit 
to  the  inmates  whatsoever.  The  impurities  exhaled  by 
human  bodies  with  less  temperature  will  rise  more 
slowly  and  less  high,  and  only  part  of  them  will  be 
forcibly  carried  away  with  the  ascending  draft.  "What 
can  be  expected  to  be  retained  in  the  saloon?  A  pro- 
portionate small  part  only  of  the  direct  supply  of 
good,  and  a  very  large  part  of  impure  air.  The  cal- 
culated mixture  and  amalgamation  will  be  only  in  a 
small  degree.  This  evil,  nevertheless,  will  remain  the 
same,  no  matter  whether  the  openings  for  escape  are 
there  or  not.  The  healthy  aif  will  in  this  case  escape 
through  occasional  accidental  openings,  particularly  in 
the  higher  strata. 

It  is  hardly  necessary  to  state  that  the  air  ventila- 
tion finds  here  its  proper  place  also,  and  that  it  is 
impossible  for  screens,  no  matter  how  they  are  made, 
to  prevent  the  evil,  and  we  may  base  on  this  so  evil  a 
circumstance,  the  cause  that  the  ventilation  through 
warmth  has  furnished  such  bad  results,  while  through 
a  mechanical  action  of  force  a  greater  agitation,  and 
consequently  a  general  mixture,  takes  place. 


88  HEATING  AND  VENTILATION. 

"  But  it  is  likewise  true  that  the  difficulties  of  the  one 
and  the  other  method  are  attached  to  each,  though  in  a 
different  degree.  In  all  arrangements  in  which  the 
hot  air  is  introduced  immediately  under  the  ceiling, 
and  the  impure  colder  air,  as  mentioned  before,  escapes 
through  heated  channels  or  flues  with  considerable 
expense,  the  great  difficulties  are  then  partially  over- 
come, but  others  before  explained  remain.  I  will  here 
mention  another  characteristic  error,  which  is  seldom 
noticed.  It  will  perhaps  set  aside  any  doubts  that  may 
still  exist.  A  large  escape-flue  is  constructed  above 
the  ceiling,  to  allow  of  an  escape  of  impure  air.  A 
strong  heat  is  introduced  in  the  upper  part  of  the  flue, 
for  the  purpose  of  gaining  a  strong  draft.  Now  let  us 
return  to  the  plain  pipe,  and  place  hot  coals,  not  on 
its  bottom,  but  on  a  wire-net  arranged  so  that  it  may 
be  raised  and  lowered  in  the  hot  air  pipe,  and  then 
hold  a  slip  of  paper  over  the  cold ;  you  will  per- 
ceive that  the  flow  of  air  becomes  weaker  the  higher 
the  wire  net  is  raised,  and  on  the  contrary  that  the 
deeper  it  is  placed,  the  quicker  will  be  the  flow ;  a 
result  which  is  easily  explained.  If  the  wire  net  or 
the  warming  spring  is  placed  in  the  middle  of  the  hot 
pipe,  the  air  volume  below  the  middle  part  of  the  hot 
pipe  will  be  of  the  same  temperature  as  that  below  the 
middle  of  the  other  hot  pipe.  Hence  it  follows  that 
the  two  air  volumes  will  hold  their  balance,  and  the 
difference  in  their  weight  above  the  middle,  would  be 
equally  as  great  as  if  the  connecting  pipe  were  placed 
at  the  same  place.  Theliigher  the  warming  spring  is 


HEATING   AND  VENTILATION.  89 

placed,  the  shorter  the  communicating  pipes  are,  the 
less  will  be  the  difference  in  weight,  and  the  less  the 
draft,  but  larger  the  expense  of  the  fire  material.  The 
aforesaid  facts  prove  how  easy  it  is  to  penetrate  any 
system  of  ventilation,  if  we  only  fall  back  upon  one  or 
the  other  simple  experiment,  by  placing  stove  pipes 
together  in  form  of  communicating  pipes.  It  cannot 
therefore  be  difficult  to  follow  every  new  case  that  may 
arise." 


HEATING   AND   VENTILATION    OF   THE    ANCIENTS. 

"  Many  will  hesitate  to  admit  that  the  ancients  were 
ever  acquainted  with  the  principles  of  economical  and 
rational  process  of  heating,  and  to  do  justice  to  the 
necessity  of  an  effectual  ventilation.  This  assumption 
will  not  alone  be  justified  by  their  knowledge  of 
science,  but  also  owing  to  their  mild  climate ;  large 
meeting-houses,  or  public  halls,  to  accommodate 
thousands  of  people  closely  huddled  together,  were 
less  in  demand  than  at  the  present  time  by  our  social 
dispositions  and  climatical  demands.  Dr.  Berger, 
however,  in  his  work,  states  that  it  is  very  interest- 
ing to  prove  that  the  ancients  in  their  simple  and 
serene  sense  of  nature  actually  did  heat  and  ventilate 
better  than  we  do  at  the  present  day,  and  adds,  that 
it  will  be  absolutely  necessary,  if  we '  intend  to  arrive 
at  some  perfection  in  this  particular,  to  fall  back  on 
the  principles  by  them  introduced.  If  we  intend  to 
make  ourselves  better  acquainted  with  their  arrange- 


90  HEATING  AND  VENTILATION. 

ments,  we  must  take  a  different  course  to  that  we  pur- 
sue with  our  present  system.  We  must,  in  the  first 
place,  become  acquainted  with  the  remains  which 
have  been  left  to  us  by  time  and  events,  and  with  the 
assistance  of  the  ancient  authors,  however  incomplete 
their  works,  the  whole  will  have  to  be  newly  con- 
structed. We  are  bound  to  inquire  first  into  the 
designation  of  the  restored  arrangements,  and  after 
all  the  previous  labor,  it  is  proper  for  us  to  enter 
upon  the  test  to  prove  the  actions  which  have  solely 
occupied  our  labor  by  the  newer  arrangements.  But 
the  proof  cannot  be  determined  there  as  here  in  the 
same  manner.  We  cannot  by  direct  experiments 
prove  how  much  fire  material  was  requisite  to  produce 
certain  heat  at  one  of  those  former  buildings,  or  how 
much  the  impurities  of  the  air  were  affected  by  exhala- 
tion and  evaporation,  and  how  much  time  it  required 
to  dispense  with  them  in  the  former  arrangement,  etc. 
To  do  this,  the  former  arrangements  have  to  be  in 
perfect  working  order.  We  have  to  follow  different 
ways ;  we  have  to  learn  from  our  own  and  by  other 
experiments  the  principles  most  depending  upon- them, 
and  then  we  have  to  ask  how  far  the  principles  have 
been  employed  by  the  ancients  or  not.  The  compari- 
son between  the  old  and  new  methods  will  then  deter- 
mine itself.  The  remains  which  will  serve  as  a  guide 
may  be  traced  nearly  entirely  from  the  Eoman  baths. 
They  are  often  found,  and  in  great  numbers,  not  alone 
in  the  warmer  parts  of  Italy,  where  the  heating  of  the 
private  houses  is  of  no  consequence,  but  likewise 


HEATING  AND  VENTILATION.  91 

in  nortliern  climates,  particularly  in  Germany  and 
France.  The  baths  in  Pompeii  and  Herculaneum 
are  mostly  in  their  original  state.  There  are  also 
remains  in  Rome  and  in  the  neighborhood,  Sero- 
fano,  etc.  In  general  they  all  exhibit  the  same  ar- 
rangement of  a  peculiar  heating  method,  but  still  there 
are  in  several  cases  various  differences,  and  those  very 
differences  will,  no  doubt,  by  close  investigation,  help  to 
raise  to  our  conception  the  acuteness  of  penetra- 
tion the  ancients  possessed  in  such  a  high  degree.  No 
doubt  the  easiest  way  to  arrive  at  a  most  correct  and 
clear  understanding  of  their  arrangements,  will  be  by 
explaining  a  number  of  examples.  We  will  commence 
with  the  winter  residence,  the  villa  Tusculana,  situa- 
ted on  a  hill  side  near  Herculaneum,  a  description  of 
which,  Winkelman  introduces  with  these  words : 
*  The  wealthier  classes  of  the  Romans  were  better 
provided  against  cold  than  we  are.  Their  stoves  heat- 
ed the  room  without  molesting  the  heads  of 
the  inmates.'  The  building  is  low ;  underneath 
the  earth  is  a  room  of  the  same  dimensions  as  the 
room  which  is  located  immediately  above  it,  about  two 
feet  in  height.  The  lower  space  or  room  is  named  the 
Hypocaustum.  In  the  last  named  room  are  small  pil- 
lars built  of  bricks,  without  mortar,  only  walled  up 
with  clay,  the  better  to  withstand  the  heat.  Upon 
those  pillars  bricks  are  laid,  and  upon  them  rests  the 
suspended  floor.  Heating  floor  called  suspensurae 
caldarium  (Balinese  pensiles).  The  floor  is  laid  with 
coarse  mosaic,  the  walls  of  the  upper  rooms  are  cov- 


92  HEATING  AND  VENTILATION. 

ered  with  different  colored  marble  slabs.  In  this  floor 
are  square  flues  walled  in,  communicating  with  the 
Hypocaustum.  These  flues  are  built  in  the  surround- 
ing walls,  and  extend  to  the  upper  or  second  story 
room,  where  the  heat  escaped  through  lions'  heads 
made  of  terra  cotta,  and  regulated  by  a  plug  or  stop- 
per. A  small  passage  leads  into  the  Hypocaustum. 
On  the  other  end  of  the  passage  is  the  heating  stove 
(Hypocausis  prsefernium,)  from  which  the  heat  enters 
through  the  passage  into  the  Hypocaustum,  and  from 
thence  through  the  flues,  so  that  the  floor  became 
heated  first,  and  afterwards  the  walls.  The  floor  of 
the  second  story,  probably  constructed  similarly  to  the 
first,  but  perhaps  of  less  thickness,  was  heated  by  the 
heat  of  the  room  below.  Such  a  general  and  equal 
diffusion  of  heat  was  not  accidental,  but  calculated. 
Therefore  Seneca  remarks,  the  lowest  and  highest 
part  receives  its  heat  equally.  This  mode  of  heating 
private  dwellings  is  also  used  for  heating  baths,  pri- 
vate as  well  as  public  baths,  and  the  most  important 
part  of  them  seems  to  be  the  hot  room  or  Caldarium. 
The  bath  of  Buxweiler  in  Alsace  had  a  somewhat  differ- 
ent arrangement  to  the  above.  The  piUars  or  piers 
supporting  the  floor  were  less  in  number,  but  the  heat- 
ing flues  were  not  close  together  as  in  the  former ;  on 
the  contrary,  a  space  was  left  between  them,  which  had 
no  openings,  except  in  the  Hypocausis,  and  an  outlet 
on  the  end  communicating  with  the  open  air.  Imme- 
diately after  the  suspended  floor  became  warm,  the 
smoke  entered  the  flues  and  escaped  through  the 


HEATING  AND  VENTILATION.  93 

upper  outlets.  The  entrance  door  was  placed  imme- 
diately over  the  fire  room,  also  at  a  place  on  the  floor 
where  the  temperature  was  the  highest,  so  that  the 
draft  of  the  air  through  the  opening  of  the  door,  was 
at  once  mixed  to  an  equal  temperature.  But  the  flues 
were  not  always  conductors  of  heat.  The  public  baths 
at  Pompeii,  for  instance,  had  double  walls  constructed 
of  burnt  tiles,  set  up  endways  with  an  open  space  of 
four  inches  secured  with  holdfasts,  so  that  the  whole 
room  was  actually  surrounded  with  a  single  air  volume. 
Is  it  not  plain,  that  this  arrangement  proves  most 
strikingly  that  the  equal  temperature,  particularly  at 
the  floor,  was  attained  in  a  most  excellent  manner,  but 
it  is  noticed,  there  is  no  preparation  made  for  ventila- 
tion ?  But  still  the  arrangement  of  the  Lichtenberger 
bath  in  Germany,  proves  that  they  recognized  the 
necessity  of  introducing  fresh  air  then  in  the  Tepida- 
rium.  The  mild  heated  bathing  room  is  entered  by  a 
canal  to  supply  fresh  air,  and  we  shall  also  find  that 
there  was  care  even  taken  for  the  escape  of  impure  and 
heated  air  to  a  sufficient  extent.  Both  were  particu- 
larly requisite  in  the  Caldarium,  the  heated  room.  It 
is  easily  comprehended  that  in  this  room  fresh  air  had 
to  be  introduced  most  cautiously.  A  great  flow  of 
quite  cold  air,  .or  of  air  alrogether  of  low  temperature, 
would  have  acted  upon  the  perspiring  multitude  not 
alone  uncomfortably,  but  very  dangerously.  The  en- 
tering air  had  first  to  be  cleared  of  its>  peculiar  and 
offensive  qualities.  It  appears  this  purpose  has  been 
gained  in  a  most  judicious  manner,  by  an  arrangement 


HEATING  AND  VENTILATION. 

which  is  illustrated  in  a  picture  found  in  the  bachs 
of  Titus.  This  picture  exhibits  next  to  the  right  two 
fires  under  two  boilers,  calculated  for  water  heat.  The 
Hypocaustum  is  divided  by  three  large  fire  canals, 
placed  on  a  level,  calculated  to  spread  under  the  en- 
tire suspended  floor.  Between  the  ceiling  of  the 
single  division  of  the  Hypocaustum  and  the  suspended 
floor  three  more  small  fires  are  placed.  Those  small 
fire  rooms  are  perhaps  nothing  more  than  a  continua- 
tion of  the  three  first  named  larger  canals,  extending 
to  an  equal  height  at  the  bottom  of  the  larger  canals 
for  firing  purpose  ;  the  fuel  is  seen  burning  ;  and  bend- 
ing over  the  Hypocaustum,  in  a  right  apgle  around, 
the  flames  are  noticed  horizontally  between  the  ceil- 
ing and  the  suspended  floor,  in  a  continued  stretch 
forward.  The  discharge  of  the  horizontal  fire  chan- 
nels may  be  traced  to  the  heating  flues,  probably  placed 
in  the  opposite  rear  wall,  but  impossible  to  be  shown 
in  the  picture.  On  the  left  side  of  the  picture,  open- 
ings are  seen  at  some  distance  from  the  floor  ;  these 
openings  which  incline  to  the  ceiling  of  the  Hypocaus- 
tum, entered  the  room  in  a  downward  flow.  In  the 
ceiling  an  outlet  was  prepared,  by  which  the  hot  air 
had  a  chance  to  escape.  This  arrangement  was  found 
in  a  bath  house  at  Serofano,  not  far  from  Borne,  and  it 
seems  to  be  general  ;  involuntarily  those  reflections 
call  to  recollection  a  former  quarrel,  which  was  carried 
on  in  the  past  age,  with  great  expenditure  of  sagacity 
and  loss  of  time  over  the  question,  whether  the 
Bomans  had  actually  chimney  stacks  or  not.  This 


HEATING  AND  VENTILATION.  95 

quarrel  is  somewhat  amusing.  One  party  was  deter- 
mined that  the  smoke  should  escape  through  the 
window  openings  in  the  walls,  through  the  roof  etc., 
and  the  other  was  determined  that  it  should  escape 
through  the  chimney.  At  the  same  time  both  parties 
were  a  unit  that  the  smoke  did  neither  pass  through 
the  window  nor  other  wall  openings,  nor  through  the 
chimney  flues,  but  through  the  heating  flues.  How- 
ever, nobody  will  lessen  the  merit  this  chimney 
quarrel  deserves,  and  it  proves  how  this  advanced 
heating  method  met  with  a  general  application  wher- 
ever heat  was  requisite  for  a  continued  purpose,  and 
by  this  method  only  could  a  perfect  result  be  ex- 
pected." 

COMPARISON   OF   THE   OLD    AND   MODERN   METHODS. 

"  The  main  difference  between  the  two  methods  can 
be  explained  very  clearly  by  simple  examples .  Take, 
for  instance,  a  stove  composed  of  terra  cotta  tiles, 
and  place  a  warming  spring,  a  gas  or  spirit  flame,  and 
as  near  the  bottom  as  possible,  and  near  to  the  side 
wall  of  the  same.  Then  examine  the  temperature, 
and  you  will  find  that  the  same  increases  from  the 
bottom  upwards  very  rapidly,  and  that  the  process  of 
heating  the  bottom  and  walls  is  slow,  and  much 
slower  at  the  bottom.  You  may  feel  that  the  air 
enters  at  the  lower  openings  very  rapidly,  and  that 
this  same  air  escapes  very  strongly  heated.  If  the 
warming  spring  or  gas  light  is  withdrawn,  the  former 


96  HEATING  AND  VENTILATION. 

phenomenon  diminishes  as  rapidly  as  it  first  appeared. 
By  placing  a  warming  spring  below  the  bottom  of  the 
stove,  then  the  walls  will  be  heated  much  more  than 
before.  The  bottom  receives  naturally,  not  a  lower  -but 
a  higher  temperature  than  the  other.  In  the  inner 
space  the  temperature  is  higher  below  than  above, 
but  in  a  short  time  the  change  may  be  the  reverse ; 
the  difference,  however,  between  the  upper  part  and 
the  lower  is  small.  The  air  which  escapes  from  the 
chimney  flue  is  by  no  means  as  hot,  and  vehement 
in  its  movement ;  it  is  on  the  contrary  slow,  constant, 
and  less  heated.  As  soon  as  the  warming  spring  is 
removed,  then  the  difference  in  warmth  between  the 
upper  and  lower  part  returns  to  its  former  proportions. 
The  constant  air  draft  continues  for  a  considerable 
time,  and  by  degrees  works  forward.  The  floor  and 
walls  have  inhaled  the  warming  spring,  and  changed 
to  warming  springs  themselves,  but  with  a  nature  not 
allowing  the  heat  to  escape  rashly,  and  spouting,  but 
sparingly,  and  in  sufficient  quantity.  The  first  of  the 
two  experiments  represents  the  heating  method  of  the 
newer  times  ;  it  furnishes  the  heat  especially  and 
rashly  upwards ;  that  means,  to  a  place  where  it  is  not 
wanted.  The  last  experiment  represents  the  method 
of  the  Romans.  This  method  furnishes  the  heat 
especially  and  quickly  into  the  lower  parts  of  the 
room  to  be  heated,  and  precisely  to  the  place  where 
wanted.  Our  methods  drive  a  considerable  part  of 
the  heat  out  of  the  chimney  flue,  without  any  service 
to  the  chief  object.  The  Romans  dispense  with  the 


HEATING  AND  VENTILATION.  97 

smoke,  but  take  the  advantage  of  it,  and  apply  its 
heat  for  heating  pnrposes ;  the  smoke  rises  between 
the  space  of  a  thick  outer  wall  and  thin  inner  wall. 
But  the  room  is  heated,  not  alone  by  the  smoke,  but 
also  through  the  heated  air  of  the  Hypocaustum ;  each 
operates  in  its  individual  capacity,  and  still  there  is 
heat  enough,  so  as  not  to  disturb  the  rising  power  of 
the  smoke.  Our  methods  confine  the  principal  bearer; 
the  other  part  of  heat,  the  movable  air ;  by  this  means 
it  will  become  as  movable  as  the  bearer,  and  with 
these  enters  rashly  to  the  upper  part  of  the  rooms, 
the  inmates  below  receive  the  rest,  which  is  impossible 
to  place  above. 

"  The  Romans  consequently  retain  this  part  in  the 
lower  strata,  not  trusting  to  the  movable  air,  but  to 
the  compactness  of  the  clay.  The  air  is  only  an  inter- 
meddler,  the  heat  is  carried  to  the  ceiling,  but  only  to 
the  ceiling  of  the  Hypocaustum.  The  heat  is  here 
concentrated  and  supplies  the  air  of  the  room  continu- 
ally, and  in  such  quantity  as  is  requisite  for  the 
inmates,  not  more;  and  not  a  particle  can  escape 
which  has  not  been  used.  Our  methods  are  calcula- 
ted to  supply  the  floor,  with  bad  warming  conductors. 
The  Eomans  construct  the  floors  also  not  with  the  very 
best  conductors  of  heat,  otherwise  they  would  have 
suffered  with  too  much  heat,  but  nevertheless  suffi- 
ciently good  without  waste  of  fuel. 

"  It  is  a  fact,  our  methods  molest  the  head  with  un- 
healthy heat,  and  leave  the  feet  cold.  The  ancient 
method  warms  the  feet  and  leaves  the  head  free. 


98  HEATING  AND  VENTILATION. 

"  Our  methods  conduct  the  heat  in  one  air  stream  of 
small  horizontal  extent,  concentrated  to  the  upper  part 
of  the  room  to  be  heated.  Close  to  the  air  current  the 
occupant  finds  himself  too  warm,  and  the  more  remote 
he  keeps  from  it  the  more  he  feels  cold,  too  cold !  all 
in  one  and  the  same  room.  The  ancients  knew  noth- 
ing of  a  hot  air  current  ;  every  where  in  the  occupied 
room,  there  was  an  equal  and  a  continued  flow  of  mild 
warm  air.  It  was  not  possible  to  find  one  part  of  the 
room  too  hot  and  the  other  too  cold.  Should  part  of  the 
floor  near  the  heating  apparatus  prove  too  hot,  then  it 
follows  that  the  colder  air  will  flow  more  rapidly. 
The  upper  rooms  of  the  ancients  prove  to  be  as  com- 
fortable as  the  lower ;  the  upper  parts  of  our  theatres 
and  concert  rooms  prove  unsupportable  for  any  length 
of  time,  even  with  a  mechanical  ventilation. 

"The  air  which  rises  in  the  flues  of  the  ancient 
arrangement,  will  furnish  heat,  and  by  this  process 
will  prevent  the  air  rising  in  the  room  from  returning 
to  the  floor.  Our  walls  and  windows  are  cold,  and  lead 
the  impure  and  refrigerant  air  repeatedly  to  the  lungs 
of  the  inmates. 

"  The  temperature  of  the  floor  and  the  walls  required 
with  the  ancients  not  to  be  more  than  the  temperature 
requisite  for  the  room,  and  it  necessarily  should  be  so. 
The  difference  of  temperature  between  the  outer  air 
and  the  air  in  the  room  could  never  be  so  great  as  the 
rising  ajr  near  a  stove,  or  from  an  air-heating  appa- 
ratus. So  whenever  the  outer  air  was  introduced,  no 
matter  in  whatever  way,  owing  to  the  difference  in 


HEATING  AND  VENTILATION.  99 

temperature,  the  inward  current  of  air  could  never 
enter  violently.  On  the  contrary,  the  colder  air  was 
forced  to  descend  gently  to  the  floor,  receive  its  warmth 
and  then  rise  again,  but  not  descend  a  second  time, 
not  meeting  with  any  cooling  process  on  the  walls  ;  and 
through  the  outlet  flue  the  warmer  and  the  mixed  im- 
purities of  the  air  escape,  without  being  inhaled  con- 
tinually. All  our  new  systems  of  ventilation  either 
produced  by  mechanical  power  or  heat,  lead,  with  few 
exceptions,  a  strong  hot  and  cold  air  current  into  the 
air  to  be  purified,  and  create  a  most  stirring  motion, 
and  cause  a  most  complete  mixture.  Those  with  heat 
connected  systems  are  calculated  for  the  greatest  dif- 
ference in  temperature,  and  carry  the  supplying  good 
air,  or  so  much  of  it  as  is  not  mixed,  quickly  through 
the  outlet  flues.  The  ancients,  however,  were  con- 
tented with  a  much  less  difference  in  temperature,  and 
lessened  the  same  accordingly.  Mixture  was  not  the 
object,  but  an  equal  rising  of  consumed  air  current 
through  corresponding  differences  of  temperature. 
Not  a  single  violent  air  current  is  introduced ;  a  great 
number  of  gentle  small  rays  are  spread  calmly  upon  the 
floor,  and  lift  the  consumed  air  equally  and  continu- 
ally upwards,  never  to  return.  A  mixture,  as  formed 
in  the  other  case,  is  impossible.  A  colossal  air  draft 
of  60  metres  for  each  person  is  not  necessary.  The 
limit  is  gained  by  a  minimum.  To  guard  against  the 
mechanical  action  of  the  strong  air  rays 'brought  in, 
and  also  against  the  action  of  the  higher  and  lower 
temperature,  screens  of  various  forms  are  introduced, 


100  HEATING  AND  VENTILATION. 

which  never  answer  the  purpose  thoroughly  ;  besides, 
a  quantity  of  air  rays  introduced  presents  another  dis- 
advantage. It  takes  too  long  a  time  to  disseminate, 
and  it  follows  that  the  current  of  air  in  a  perfectly  clear 
condition,  acts  only  in  a  confined  and  local  way,  and 
never  in  a  general  way.  The  ancients  introduce  the 
warmer  air  in  fine  rays  on  all  sides,  and  so  remove  all 
objections.  But  this  gentle  withdrawal  in  this  gradual 
manner,  has  a  great  advantage  over  our  treatment ;  and 
to  illustrate  it  more  clearly,  some  well  known  facts  are 
necessary  to  be  here  introduced.  Whenever  the  door 
of  a  heated  room  is  opened,  then  the  cold  air  enters  at 
the  bottom  of  the  opening,  but  escapes  at  the  upper 
part ;  a  light  will  clearly  prove  this,  if  applied  to  the 
opening.  Whenever  a  window  is  opened,  the  same 
movement  is  noticed,  no  matter  how  large  or  small  the 
windows  may  be,  or  no  matter  in  what  position  the 
window  is  placed,  at  the  lower  or  at  the  upper  part  of 
the  heated  room.  The  cause  of  this  phenomenon  is 
well  known  :  the  cold  air  forces  itself  in  at  the  lower 
part,  and  the  warmer  air  must  escape  at  the  upper 
part,  and  the  consequence  is  that  the  exit  of  air  stops 
at  the  window  at  the  time  an  opening  is  placed  above 
the  window.  The  well-known  method  of  ventilation, 
in  which  a  hollow  cylinder,  divided  longitudinally  into 
two  parts,  and  placed  in  the  wall  or  ceiling,  rests  upon 
the  same  principle.  Now  we  can  form  a  clear  view  of 
what  is  called  a  voluntary  and  natural  ventilation. 
The  numerous  pores  in  the  materials  are  so  many  ducts 
for  the  inlet  and  outlet  of  air,  and  the  change  of  air 


HEATING  AND  VENTILATION.          101 

through  those  pores  takes  place  as  indicated.  By  due 
reflection,  it  is  easily  seen  that  the  ventilation  of  the 
ancients  conforms  to  the  imitation  of  the  natural  ven- 
tilation. When  the  cooler  air  enters  from  a  lower 
opening  of  a  flue  into  a  heated  room,  the  warm  and 
supplanted  air  rises  in  the  next  higher  opening  of  the 
heated  flues,  an  occurrence  which  repeats  itself 
throughout  the  room,  below  and  above  and  on  all 
sides.  So  the  impure  air  travels  only  one  way  to  the 
outlet,  the  impure  air  is  not  lifted  from  the  floor  to  the 
ceiling,  every  sheet  of  air  requires  only  to  rise  gradu- 
ally. It  is  clear  that  through  this  process  the  desired 
result  is  most  surely  gained.  It  is  otherwise  with  our 
newer  method,  where  the  air  generally  enters  at  the 
lower  part  and  escapes  at  the  upper  part,  equally  so  as 
the  accumulating  impurities  move  through  the  whole 
height  of  the  saloon,  and  where  the  heated  air  forms 
its  exit  through  the  opening  arranged  as  above,  where- 
as the  lower  impurities,  not  ascending  so  high,  remain 
behind.  The  dwelling  rooms  and  bath  rooms  of  tho 
ancients  were  at  an  average  not  so  high  as  ours,  and 
it  was  not  necessary  they  should  be.  By  our  methods 
it  is  important  that  in  the  mixture  of  pure  and  impure 
air,  the  pure  air  should  be  in  a  sufficient  healthy  sur- 
plus. 

"  The  larger  and  higher  the  rooms  are,  the  better. 
The  ancients  required  no  such  elevation  ;  on  the 
contrary,  by  the  process  of  lifting  the  impure  air  grad- 
ually, the  interest  of  economy  was  applied,  to  keep  the 
rooms  low  ;  every  extension  of  height  requisite  for  hab- 


102  HEATING  AND'' VENTILATION. 

itable  rooms  is  actually  an  extravagant  consumption, 
requiring  more  heat.  The  heating  and  ventilation 
conception,  however,  to  which  we  have  accustomed 
ourselves,  will  naturally  restrain  us ;  but  as  soon  as  we 
acknowledge  £he  advantage  of  the  arrangements  of  the 
ancients,  with  good  air  equally  distributed,  then  we 
shall  require  less  room  for  the  accumulation  of  good 
air.  The  finest  mosaic  work  and  ornaments  for  floors 
and  walls  of  the  ancient  works,  are  known.  They  form 
a  contrast  to  the  newer  works,  and  the  contrast  of  the 
practice  of  using  in  the  one  case  good  and  in  the  other 
bad  warming  conductors,  is  in  favor  of  the  ancients, 
with  a  corresponding  claim  to  art  also.  It  is  hardly 
possible  to  suppose  that  there  could  be  any  opposition 
to  the  hope  that  theory  only  has  been  preached,  with- 
out experience .  Experience  is  in  advance  of  theory 
at  least  two  thousand  years,  and  is  introduced  by 
economical,  practical  and  judicious  men,  by  men  every 
way  trustworthy.  The  main  object  here  is  only  the 
first  trial  in  a  time  of  flourishing  science,  to  form  a 
comparison  of  the  results  with  those  of  newer  methods 
of  heating  in  connection  with  ventilation.  Then  when 
this  first  trial  has  been  made,  I  think  it  will  be  unne- 
cessary to  say  anything  more  in  its  favor ;  it  will  speak 
for  itself.  All  that  is  left  to  be  done  is  this,  to  perfect 
this  method  by  still  more  experience  and  through  sci- 
ence. 

"  Then  the  combat  between  ventilation  through  heat 
or  through  mechanical  power,  will  subside  in  itself. 
We  have,  in  this  system,  economical  heating  connected 


HEATING   AND  VENTILATION.  103 

with  the  natural  ventilation.  Hitherto  the  trifling 
effects  of  the  natural  and  voluntary  ventilation,  through 
the  pores  of  the  walls  and  other  accidental  openings, 
it  was  taken  for  granted  could  be  assisted  in  two  differ- 
ent ways,  and  so  the  natural  ventilation  may  be  ele- 
vated to  its  greatest  perfection,  and  if  not  found  suffi- 
cient in  all  cases,  then  the  mechanical  power  may  as- 
sist, by  forcing  the  pure  air  perhaps  through  the  same 
air  flues,  through  which  the  voluntary  air  may  enter. 
There  is  no  comparison  more  between  tiie  two  meth- 
ods. It  will  not  be  questionable,  the  one  or  the  oth- 
er, but  one  alone,  or  in  connection  with  the  other — a 
question  which  will  easily  be  settled  by  a  strict  in- 
quiry into  the  condition  of  the  air  in  single  rooms." 


CATALOGUE 


OF 


SCIENTIFIC  BOOKS, 


PUBLISHED   BY 


D.  VAN  NOSTRAND, 

23  MURRAY  STREET  AND  27  WARREN  STREET, 
PUBLISHER,  IMPORTER  AND  BOOKSELLER 


NEW    YORKi 

1872 


%*  Copies  of  this  Catalogue,  and  also  Catalogue  of  Military 
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application. 


VALUABLE  WORKS 


ON 


BRIDGE  CONSTRUCTION, 


PUBLISHED    BY 


D.  VAN  NOSTRAND, 

23  MURRAY  STREET  and  27  WARREN  STREET,  N.  Y. 


LONG  AND  SHORT  SPAN  RAILWAY  BRIDGES.     By 

John  A.  Roebling,  C.  E.  Illustrated  with  16  large 
finely  executed  Copper-plate  Engravings  of  Views 
and  Plans,  together  with  an  Engraved  Steel  Plate 
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IRON  RAILWAY  BRIDGE  AT  QUINCY,  ILL.     By 

Thomas  Curtis  Clarke,  Chief  Engineer.     Illustrat  d 

with  27  Lithographed  Plans,     i  vol.  4to,  cloth 7  50 

IRON  TRUSS  BRIDGES  FOR  RAILROADS.  Methods 
of  Calculating  Strains,  with  a  Comparison  of  the  most 
Prominent  Truss  Bridges,  and  new  Formulas  for 
Bridge  Computations.  By  Brevet-Col.  Wm.  E.  Mer- 
rill, Major  Corps  of  Engineers.  Illustrated  with  9 
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KANSAS  CITY  BRIDGE.  With  an  Account  of  the  Reg- 
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D-    VAX    /.PxSTRAXD'S    PUBUCATIOKS. 

UBBOT  (H.  L.)  Shge  Artiller}'  in  the  Campaign  against 
Richmond,  vr,th  Notes  on  the  1 5-inch  Gun,  including 
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ALEXANDER  (J.  H.)  Universal  Dictionary  of  Weights 
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BENET  (S.  V.)  Electro-Ballistic  Machines,  and  the  Schultz 
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Assistant  Engineer.  Illustrated  with  five  lithographic 
views  and  twelve  plates  of  plans.  4to,  cloth 6 .  OO 

KcCORMICK  (R.  C.).  Arizona  :  Its  Resources  and  Pros- 
pects. By  Hon.  R.  C.  McCormick.  With  map,  8vo, 


It,   TAN  KOSTaAND'S   PUBLICATIONS. 

1ONIFIE  (Win.)  Mechanical  Drawing.  A  Text-Book 
of  Geometrical  Drawing  for  the  use  of  Mechanics  and 
Schools,  in  which  the  Definitions  and  Rules  of  Geometry 
are  familiarly  explained ;  the  Practical  Problems  are  ar- 
ranged, from  the  most  simple  to  the  more  complex,  and 
in  their  description  technicalities  are  avoided  as  much 
as  possible.  With  illustrations  for  Drawing  Plans,  Sec- 
tions, and  Elevations  of  Buildings  and  Machinery;  an 
Introduction  to  Isometrical  Drawing,  and  an  Essay  on 
Linear  Perspective  and  Shadows.  Illustrated  with  over 
200  diagrams  engraved  on  steel.  By  Wm.  Minifie, 
Architect.  Seventh  Edition.  With  an  Appendix  on 
the  Theory  and  Application  of  Colors,  i  vol.  8vo, 
cloth $4  oo 

WILLIAMSON.  Practical  Tables  in  Meteorology  and 
Hypsometry,  in  connection  with  the  use  of  the 
Barometer.  By  Col.  R.  S.  Williamson,  U.  S.  A. 
i  vol.  4to,  flexible  cloth 2 . 50 

CULLEY.  A  Hand-Book  of  Practical  Telegraphy.  By 
R.  S.  Culley,  Engineer  to  the  Electric  and  Interna- 
tional Telegraph  Company.  Fourth  edition,  revised 
and  enlarged.  Svo.  Illustrated.  Cloth 5  .OO 

POPE.  Modern  Practice  of  the  Electric  Telegraph.  For 
Electricians  and  Operators.  By  Frank  L.  Pope. 
Fourth  edition,  revised  an-1  illustrated.  Svo,  cloth. .  2.00 

MINIFIE  (Wm.)  Geometrical  Drawing.  Abridged  from 
the  Octavo  edition,  for  the  use  of  Schools.  Illustrated 
with  48  steel  plates.  Fifth  edition,  i  vol.  I2mo, 
cloth 2 .  oo 

*  It  is  well  adapted  as  a  text-book  of  drawing  to  be  need  In  our  High  School*  and 
academies  where  this  useful  branch  of  the  fine  arU  has  been  hitherto  too  muc 
'— Boston  Journal. 

7 


D.  TAN   NOSTRANP'S   PUBLICATIONS. 

FIERCE  (Prof.  Bcnj.)  System  of  Analytical  Mechanics. 
Physical  and  Celestial  Mechanics,  by  Benjamin  Pierce, 
Perkins  Professor  of  Astronomy  and  Mathematics  in 
Harvard  University,  and  Consulting  Astronomer  of  the 
American  Ephemcris  and  Nautical  Almanac.  Developed 
in  four  systems  of  Analytical  Mechanics,  Celestial  Me- 
chanics, Potential  Physics,  and  Analytic  Morphology. 
i  vol.  410,  cloth $ i o . oo 

"I  have  re-examined  the  memoirs  of  the  great  geometers,  and  have  striven  to  consoli- 
date their  latest  researches  and  their  most  exalted  forms  of  thorght  into  a  consistent  ant 
uniform  Ueatise.  If  I  have  hereby  succeeded  in  opening  to  the  students  of  my  country  a 
readier  access  to  these  choice  jewels  of  intellect;  if  their  brilliancy  is  not  impaired  in  this 
attempt  to  reset  them;  if,  in  their  own  constellation,  they  illustrate  each  other,  and  con- 
centrate a  stronger  light  upon  the  names  of  their  discoverers;  and,  still  more,  if  any  gem 
which  I  may  have  presumed  to  add  is  not  wholly  lustreless  in  the  collection,— I  siiall  feel 
that  my  work  has  not  been  in  vain."— Extract  from  the  Preface. 

PLYMPTON.  The  Blow-Pipe  ;  a  System  of  Instruction  in 
its  Practical  Use,  being  a  Graduated  Course  of  Analy- 
sis for  the  Use  of  Students  and  all  those  engaged  in  the 
Examination  of  Metallic  Combinations.  Second  edi- 
tion, with  an  appendix  and  a  copious  index.  By  Geo, 
W.  Plympton,  of  the  Polytechnic  Institute,  Brooklyn. 
l  vol.  izmo,  cloth 2.00 

FOOK  (S.  M.)  Method  of  Comparing  the  Lines  and 
Draughting  Vessels  Propelled  by  Sail  or  Steam.  In- 
cluding a  chapter  on  Laying  off  on  the  Mould-Loft 
Floor.  By  Samuel  M.  Pook,  Naval  Constructor.  I 
vol.  8vo,  with  illustrations,  cloth 5 .00 

RANDALL'S  OTARTZ  OPERATOR'S  HAND-BOOK.    By 

P.  M.  Randall.     New  edition,  revised  and  enlarged. 
Fully  illustrated.     i2mo,  cloth 2  oo 

EOGERS  (H.  D.)  Geology  of  Pennsylvania.  A  complete 
Scientific  Treatise  on  the  Coal  Formations.  By  Henry 
D.  Rogers,  Geologist.  3  vols.  410,  plates  and  maps. 
Boards 30.00 

8 


D.  TAN  NOSTIXAHD'S  PUBLICATION*. 


SUBMARINE  BLASTING  IN  BOSTON  HARBOR, 
MASSACHUSETTS.  Removal  of  Tower  and  Cor- 
win  Rocks.  By  John  G.  Foster,  Lieutenant-Colonel 
of  Engineers,  and  Brevet  Major-General,  United 
States  Army.  With  illustrations.  4to,  cloth $3  50 

BHAFFNER  (T.  P.)  Telegraph  Manual.  A  complete 
History  and  Description  of  the  Semaphoric,  Electric, 
and  Magnetic  Telegraphs  of  Europe,  Asia,  and  Africa, 
with  625  illustrations.  By  Tal.  P.  Shaffher,  of  Ken- 
tucky. New  edition,  i  vol.  8vo,  cloth,  850  pp. ...  6.  JO 

SILVERSMITH  (Julius).  A  Practical  Hand-Book  for  Mi- 
nera,  Metallurgists,  and  Assayers,  comprising  the  most 
recent  improvements  in  the  disintegration,  amalgama 
tion,  smelting,  and  parting  of  the  Precious  Ores,  with  a 
Comprehensive  Digest  of  the  Mining  Laws.  Greatlt 
augumented,  revised,  and  corrected.  By  Julius  Silver- 
smith. Fourth  edition.  Profusely  illustrated.  I  vol. 
1 2mo,  cloth 3 .00 

SIMM'S  LEVELLING.  A  Treatise  on  the  Principles  and 
Practice  of  Levelling,  showing  its  application  to  pur- 
poses of  Railway  Engineering  and  the  Construction 
of  Roads,  &c.  By  Frederick  W.  Simms,  C.  E. 
From  the  fifth  London  edition,  revised  and  corrected, 
with  the  addition  of  Mr  Law's  Practical  Examples 
for  Setting  Out  Railway  Curves.  Illustrated  with 
three  lithographic  plates  and  numerous  wood-cuts. 
8vo,  cloth a .  50 

SUBMARINE  WARFARE,  Offensive  and  Defensive, 
including  a  Discussion  of  the  Offensive  Torpedo 
System.  By  Lieut -Commander  J.  S.  Barnes,  U.S.N. 
With  illustrations.  8vo,  cloth 5.00 


D,    VAN    NOSTRAND  S   PUBLICATIONS. 


PLATTNER'S  BLOW-PIPE  ANALYSIS.  A  Complete 
Guide  to  Qualitative  and  Quantitative  Examinations 
with  the  Blow-Pipe.  Revised  and  enlarged  by  Prof. 
Richter,  Freiberg.  Translated  from  the  latest  Ger- 
man edition  by  Henry  B.  Cornwall,  A.  M.,  E.  M 
8vo,  cloth , $7 . 50 

SPHERICAL  ASTRONOMY.  By  F.  Brunnow,  Ph.  Dr. 
Translated  by  the  Author  from  the  Second  German 
edition.  I  vol.  8vo,  cloth 6 . 50 

8TILLMAN  (Paul).  Steam  Engine  Indicator,  and  the  Im- 
proved Manometer  Steam  and  Vacuum  Gauges — their 
Utility  and  Application.  By  Paul  Stillman.  New 
edition.  I  vol.  I2mo,  flexible  cloth l  .00 

"The  purpose  of  this  useful  volume  is  to  bring  to  the  notice  of  the  numerous  class  of 
(hoee  interested  in  the  building  and  the  use  of  steam  engines,  the  economy  and  safety  attend- 
ing the  use  of  the  instrument  therein  described.  The  Manometer  has  been  long  used— the 
inventor  is  Watt  in  a  cruder  form;  and  the  forms  herein  described  are  patented  by  the 
author.  The  language  of  the  author,  the  diagrams,  and  the  scientific  mode  of  treatment 
recommend  the  book  to  the  careful  consideration  of  all  who  have  engines  in  their  care."— 
Boston  Post. 

SWEET  (S.  H.)  Special  Report  on  Coal ;  showing  its  Dis- 
tribution, Classification,  and  cost  delivered  over  different 
routes  to  various  points  in  the  State  of  New  York,  and 
the  principal  cities  on  the  Atlantic  Coast.  By  S.  H. 
Sweet.  With  maps,  i  vol.  8vo,  cloth 3 .00 

WILLIAMSON.  Practical  Tables  in  Meteorology  and 
Hypsometry,  in  connection  with  the  use  of  the 
Barometer.  By  Col.  R.  S.  Williamson,  U.  S.  Army. 
4to,  flexible  cloth a .  S'j 

WALKER  (W.  H.)  Screw  Propulsion.  Notes  on  Screw 
Propulsion,  its  Rise  and  History.  By  Capt.  W.  H. 
Walker,  U.  S.  Navy.  I  vol.  8 vo,  cloth 75 

"After  thoroughly  demonstrating  the  efficiency  of  the  screw,  Mr.  Walker  proceeda  to 
point  out  the  various  other  points  to  be  attended  to  in  order  to  secure  an  efficient  man  of - 
irar,  and  eulogizes  throughout  the  readinesa  of  the  British  Admiralty  to  test  every  nov- 
eity  calculated  to  give  satisfactory  results.  *  *  *  *  Commander  Walker's  book  con- 
tains an  immense  amount  of  concise  practical  data,  and  every  item  of  information  r<r 
Krded  fully  proves  that  the  various  points  bearing  upon  it  have  been  well  coasid^-t-d 
previously  to  expressing  an  opinion."— Londnn  Mining  Journal 

JU 


D.  VAN  NOSTBAND'S  PUBLICATIONS. 

WEISBACH'S  MECHANICS.  New  and  revised  edition. 
A  Manual  of  the  Mechanics  of  Engineering,  and  of 
the  Construction  of  Machines.  By  Julius  Weisbach, 
PH.  D.  Translated  from  the  fourth  augmented  and 
improved  German  edition,  by  Eckley  B.  Coxe,  A..  M., 
Mining  Engineer.  Vol.  I. — Theoretical  Mechanics. 
i  vol.  8vo,  i,  100  pages,  and  902  wood-cut  illustra- 
tions, printed  from  electrotype  copies  of  those  of  the 

best  German  edition $10.00 

ABSTRACT  OF  CONTENTS. — Introduction  to  the  Cal- 
culus— The  General  Principles  of  Mechanics — Pho- 
ronomics,  or  the  Purely  Mathematical  Theory  of 
Motion — Statics  of  Rigid  Bodies — The  Application 
of  Statics  to  Elasticity  and  Strength — Dynamics  of 
Rigid  Bodies — Statics  of  Fluids — Dynamics  of  Fluids 
—The  Theory  of  Oscillation,  etc. 

"  The  present  edition  is  an  entirely  new  work,  greatly  extended  and  very  much  im- 
proved. It  forms  a  text-book  which  must  find  its  way  into  the  hands,  not  only  of  every 
student,  but  of  every  engineer  who  desires  to  refresh  his  memory  or  acquire  clear  ideal 
on  doubtful  points."— The  Technologist. 

WARD  (J.  H.)  Steam  for  the  Million.  A  popular  Trea- 
tise on  Steam  and  its  Application  to  the  useful  Arts, 
especially  to  Navigation.  By  J.  H.  Ward,  Com- 
mander U.  S.  Navy.  New  and  revised  edition,  i 
vol.  8vo,  cloth I .  oo 

WHILDEN  (J.  K.)  On  the  Strength  of  Materials  used 
m  Engineering  Construction.  By  J.  K.  Whilden. 
i  vol.  1 2mo,  cloth 2 .  oo 

WILLIAMSON  (R.  S.)  On  the  use  of  the  Barometer  on 
Surveys  and  Reconnaissances.  Part  I.  Meteorology 
in  its  Connection  with  Hypsometry.  Part  II.  Ba- 
rometric Hypsometry.  By  R.  S.  Williamson,  Bvt. 
Lieut. -Col.  U.  S.  A.,  Major  Corps  of  Engineers. 
With  Illustrative  Tables  and  Engravings.  Paper 
No.  15,  Professional  Papers,  Corps  of  Engineers. 

i  vol.  4to,  cloth , 15  oo 

11 


D.  TAN  NOSTRAND'S  PUBLICATIONS. 


EOEBLING  (J.  A.)  Long  and  Short  Span  Railway 
Bridges.  By  John  A.  Roebling,  C.  E.  Illustrated 
with  large  copperplate  engravings  of  plans  and  views. 
Imperial  folio,  cloth $25.0x3 

CLARKE  (T.  C.)  Description  of  the  Iron  Railway 
Bridge  over  the  Mississippi  River,  at  Quincy,  Illi- 
nois. By  Thomas  Curtis  Clarke,  Chief  Engineer. 
Illustrated  with  27  lithographed  plans.  I  vol.  8w, 
cloth 7  50 

TUNNEB  (P.)  A  Treatise  on  Roll-Turning  for  the 
manufacture  of  Iron.  By  Peter  Tunner.  Trans- 
lated and  adapted  by  John  B.  Pearse,  of  the  Penn- 
sylvania Steel  Works,  with  numerous  engravings 
and  wood-cuts,  i  vol.  8vo,  text,  and  fol.  vol.  Plates, 
cloth IO.OO 

ISHEEWOOD  (B.  F.)  Engineering  Precedents  for  Steam 
Machinery.  Arranged  in  the  most  practical  and 
useful  manner  for  Engineers.  By  B.  F.  Isher- 
wood,  Civil  Engineer,  U.  S.  Navy.  With  illustra- 
tions. Two  volumes  in  one.  8vo,  cloth 2 . 50 

.5ATJEIIMAN.  Treatise  on  the  Metallurgy  of  Iron,  con- 
taining outlines  of  the  History  of  Iron  Manufacture, 
methods  of  Assay,  and  analysis  of  Iron  Ores,  pro- 
cesses of  manufacture  of  Iron  and  Steel,  etc.,  etc. 
By  H.  Bauerman.  First  American  edition.  Re- 
vised and  enlarged,  with  an  appendix  on  the  Martin 
Process  for  making  Steel,  from  the  report  of  Abram 
S.  Hewitt.  Illustrated  with  numerous  wood  engra- 
vings. 1 2mo,  cloth 2 . 50 

"This  is  an  important  addition  to  the  stock  of  technical  works  published  In  thta 
country.  It  embodies  the  latest  facts,  discoveries,  and  processes  connected  with  UM 
manufacture  of  iron  and  steel,  and  should  be  in  the  hands  of  every  person  interested  la 
the  subject,  as  well  as  in  all  technical  and  scientific  libraries."— Scientific  American. 

PEET.    Manual  of  Inorganic  Chemistry  for  Students. 
By  the  late  Dudley  Peet,  M.  D.     Revised  and  cn«» 
larged  by  Isaac  Lewis  Peet,  A.  M.     i8mo,  cloth. . .         75 
12 


D.  VAN  NOBTBAND'S  PUBLICATIONS. 


NUGENT.  Treatise  on  Optics  :  or,  Light  and  Sight,  the- 
oretically and  practically  treated  ;  with  the  applica- 
tion to  Fine  Art  and  Industrial  Pursuits.  By  E. 
Nugent.  With  one  hundred  and  three  illustrations. 
i  2 mo,  cloth $2.OO 

"  Tliis  book  is  of  a  practical  rather  than  a  theoretical  kind,  and  is  designed  to  afford 
accurate  and  complete  information  to  all  interested  in  applications  of  the  science.— Bound 

Prtfe. 

SABINE.  HISTORY  AND  PROGRESS  OP  THE  ELEC- 
TRIG  TELEGRAPH.  By  Robert  Sabine,  C.E.  2d 
edition,  with  additions.  Fully  illustrated,  iimo,  clo.  1.75 

GLYNN  ( J. )  Treatise  on  the  Power  of  Water,  as  applied 
to  drive  Flour  Mills,  and  to  give  motion  to  Tur- 
bines and  other  Hydrostatic  Engines.  By  Joseph 
Glynn.  Third  edition,  revised  and  enlarged,  with 
numerous  illustrations.  1 2 mo,  cloth l  •  *5 

PRIME.  TREATISE  ON  ORE  DEPOSITS.  By  Bern- 
hard  Von  Cotta.  Translated  from  the  Second  Ger- 
man edition  by  Frederick  Prime,  Jr.,  Mining  Engi- 
neer, and  revised  by  the  Author.  With  numerous 
illustrations.  8vo,  cloth 4 .  oo 

HUMBER.  A  Handy  Book  for  the  Calculation  of  Strains 
in  Girders  and  similar  Structures,  and  their  Strength, 
consisting  of  Formulae  and  corresponding  Diagrams, 
with  numerous  details  for  practical  application.  By 
William  Humber.  I2mo,  fully  illustrated,  Cloth...  1.5* 

GILLMORE.  Engineer  and  Artillery  Operations  against 
Charleston,  1863.  By  Major-General  Q.  A.  Gill- 
more.  With  76  lithographic  plates.  8vo,  cloth  ...  10.00 

•  Supplementary  Report  to  the  above,  with  7  litho- 
graphed maps  and  views.  8vo,  cloth 5 .00 

13 


D.  VAN  Nl/STRAND'S  PUBLICATIONS 

AUCHINCLOSS,  Link  and  Valve  Motions  Simplified. 
Illustrated  with  37  wood  cuts,  and  21  lithographic 
plates,  together  with  a  Travel  Scale,  and  numerous 
useful  Tables.  By  W.  S.  Auchincloss.  8vo.,  cloth,  $3  oc 

JOYNSOU.    METALS   USED   IN   CONSTRUCTION- 

Iron,  Steel,  Bessemer  Metal,  etc.,  etc.     With  illus- 
trations.    1 2mo,  cloth 75 

THE  ART  OF  GRAINING.  How  Acquired  and  How 
Produced.  By  Pickert  and  Metcalf.  Beautifully 
Illustrated,  tinted  paper.  8vo.  In  press 

VAN  BUREN.  Investigations  of  Formulas,  for  the  strength 
of  the  Iron  parts  of  Steam  Machinery.  By  J.  D.  Van 
Buren,  Jr.,  C.  E.  Illustrated,  8vo.,  cloth, 2  oc 

JOYNSON.      Designing  and   Construction  of  Machine 

Gearing.    Illustrated,  8vo.,  cloth, *  oo 

COIGNET-BETON,  and  other  Artificial  Stone.     By  Q.  A. 

Gillmore.    Illustrated  with  9  Plates.     8 vo,  cloth 2.504 

FREE  HAND  DRAWING,  a  Guide  to  Ornamental,  Fig- 
ure and  Landscape  Drawing.  By  an  Art  Student. 
Profusely  illustrated,  1 8mo.,  cloth, 75 

THE  EARTH'S  CRUST.     A  handy  Outline  of  Geology. 

By  Dav'd  Page.     Illustrated,  i8mo.,  cloth, 75 

DICTIONARY  of  Manufactures,  Mining,  Machinery,  and 
the  Industrial  Arts.  By  George  Dodd.  lamo., 

ClOth, 2    OG 


D.  TAN  NOBTHAND'S  PUBLXCATZOXS. 

MAYER.     Lecture  Notes  on   Physics.     By  Alfred  M. 

Mayer,  Ph.  D.     8vo,  cloth $2 .00 

A  TREATISE  ON  THE  RICHARDS  STEAM-ENGINE 
INDICATOR,  with  Directions  for  its  Use.  By  Chas. 
T.  Porter.  Revised  with  notes  and  large  additions, 
as  developed  by  American  Practice,  with  an  Appendix 
containing  useful  formulae  and  rules  for  Engineers. 
By  F.  W.  Bacon,  M.  E.,  Member  of  the  American 
Society  of  Civil  Engineers.  i8mo,  illustrated.  Cloth,  i.oo 

ON  THE  FILTRATION  OF  RIVER  WATERS,  for  the 

Supply  of  Cities,  as  practised  in  Europe,  made  to  the 
Board  of  Water  Commissioners  of  the  City  of  St. 
Louis.  By  J.  P.  Kirkwood,  Civil  Engineer.  Illus- 
trated by  30  engravings.  4to,  cloth 15 .00 

THE  PLANE-TABLE  AND  ITS  USE  IN  TOPOGRAPH- 
ICAL SURVEYING.  From  the  Papers  of  the  U. 
S.  Coast  Survey.  8vo,  illustrated.  Cloth 2 .  oo 

REPORT  on  Machinery  and  Processes  of  the  Industrial 
Arts  and  Apparatus  of  the  Exact  Sciences.  By  F.  A. 
P.  Barnard,  LL.  D.  Paris  Universal  Exposition, 
1867.  i  vol.  8vo,  cloth 5.00 

IRON  TRUSS  BRIDGES  FOR  RAILROADS.   The 

Method  of  Calculating  Strains  in  Trusses,  with  a 
ICareful  Comparison  of  the  most  Prominent  Trusses  in 
Reference  to  Economy  in  Combination,  etc.  By 
Brevet  Colonel  William  E.  Merrill,  U.  S.  A.  Illus- 
trated, 4to,  cloth 5 .00 

USEFUL  INFORMATION  FOR  RAILWAY  MEN. 
By  W.  G.  Hamilton,  Engineer.  Fourth  edition,  re- 
vised and  enlarged.  600  pp.  Morocco  gilt.  For 
pocket. i.c* 


VAN  NOSTRAND'S 
ECLECTIC 

ENGINEERING   MAGAZINE. 


112  PAGES,  LARGE  8vo,  MONTHLY. 

First  Number  was  Issued  Jan.  i,  1869 

ILLUSTRATED. 

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professional  newspapers  ;  none  can  afford  the  time  to  wade 
through  the  columns  of  the  whole  scientific  press  to  get  at  the 
really  important  news,  information,  and  opinions. 

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and  cost  that  all  can  afford,  the  cream  of  not  less  than  fifty  engi 
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